BIOL 101 Complete Study Guide Unit 1: DNA, RNA, and Genetics 1. DNA structure What is DNA? DNA stands for deoxyribonucleic acid. It stores the genetic information that tells cells how to function, grow, and reproduce. What is the shape of DNA? DNA has a double-helix shape, which looks like a twisted ladder. What are the building blocks of DNA? Nucleotides. What are the three parts of a DNA nucleotide? * A phosphate group * A five-carbon sugar called deoxyribose * A nitrogenous base What are the four nitrogenous bases in DNA? * Adenine (A) * Thymine (T) * Cytosine (C) * Guanine (G) What are the DNA base-pairing rules? * Adenine pairs with Thymine (A–T). * Cytosine pairs with Guanine (C–G). What does complementary base pairing mean? Each DNA base has a specific partner. Knowing one DNA strand allows you to determine the matching strand. Example: * Original: A T C G * Complement: T A G C What holds the two DNA strands together? Hydrogen bonds between the nitrogenous bases. 2. DNA vs. RNA What is RNA? RNA stands for ribonucleic acid. It helps use the genetic instructions stored in DNA to make proteins. What are the main differences between DNA and RNA? DNA RNA Usually double-stranded Usually single-stranded Contains deoxyribose sugar Contains ribose sugar Uses thymine (T) Uses uracil (U) Stores genetic information Helps make proteins What are the four bases in RNA? * Adenine (A) * Uracil (U) * Cytosine (C) * Guanine (G) What replaces thymine in RNA? Uracil. What are the three main types of RNA? * mRNA (messenger RNA): Carries genetic instructions from DNA to the ribosome. * tRNA (transfer RNA): Brings amino acids to the ribosome. * rRNA (ribosomal RNA): Makes up part of the ribosome and helps build proteins. 3. DNA replication What is DNA replication? DNA replication is the process of making an identical copy of DNA before a cell divides. Why is DNA replication important? It ensures that each new cell receives a copy of the genetic information. What does semiconservative replication mean? Each new DNA molecule contains one original strand and one newly made strand. What enzyme unzips DNA? Helicase. What enzyme adds new DNA nucleotides? DNA polymerase. What enzyme connects DNA fragments on the lagging strand? DNA ligase. What is the leading strand? The strand that is copied continuously in the direction of the replication fork. What is the lagging strand? The strand that is copied in short sections called Okazaki fragments. What are Okazaki fragments? Short pieces of newly made DNA that form on the lagging strand. What is the job of DNA ligase? It joins the Okazaki fragments together. What are telomeres? Protective sections of DNA found at the ends of chromosomes. What is the purpose of telomeres? They help protect important genetic information from being lost when DNA is copied. What is DNA repair? The process cells use to identify and correct mistakes or damage in DNA. 4. Transcription What is transcription? Transcription is the process of copying genetic information from DNA into mRNA. Where does transcription happen in eukaryotic cells? In the nucleus. What enzyme helps make RNA during transcription? RNA polymerase. What is the purpose of transcription? To create an mRNA copy of a gene that can be used to make a protein. What are the RNA base-pairing rules? * DNA A pairs with RNA U. * DNA T pairs with RNA A. * DNA C pairs with RNA G. * DNA G pairs with RNA C. Example: DNA: A T C G RNA: U A G C What happens to mRNA before it leaves the nucleus in eukaryotic cells? It undergoes RNA processing. What are introns? Sections of RNA that are removed during RNA processing. What are exons? Sections that remain and are joined together to form mature mRNA. What is RNA splicing? The removal of introns and joining of exons. 5. Translation What is translation? Translation is the process of using mRNA instructions to build a protein. Where does translation happen? At the ribosomes in the cytoplasm or on the rough endoplasmic reticulum. What is a codon? A group of three mRNA bases that codes for an amino acid or a stop signal. What is an anticodon? A group of three bases on tRNA that pairs with a matching mRNA codon. What is the role of tRNA? It carries amino acids to the ribosome. What is the role of the ribosome? It reads mRNA and connects amino acids to build a protein. What is the start codon? AUG. What amino acid does AUG code for? Methionine. What are the three stop codons? * UAA * UAG * UGA What happens when a stop codon is reached? Translation ends, and the completed protein is released. 6. Gene expression and regulation What is gene expression? Gene expression is the process of using information from a gene to make a functional product, such as a protein. What is gene regulation? Gene regulation controls when, where, and how much a gene is expressed. Why is gene regulation important? It allows cells to perform different functions even though many cells contain the same DNA. What is an operon? A group of genes controlled together, commonly found in bacteria. What is the lac operon? A group of bacterial genes involved in breaking down lactose. What happens when lactose is present? Lactose helps remove the repressor’s blockage, allowing the genes to be expressed. What happens when lactose is absent? The repressor binds to the operator and prevents the genes from being expressed. Unit 2: Evolution and Natural Selection 1. Understanding evolution What is evolution? Evolution is the change in inherited characteristics of a population over generations. Does an individual organism evolve during its lifetime? No. Populations evolve over generations. What is a population? A group of individuals of the same species living in the same area. What is a species? A group of organisms that can reproduce with one another and produce fertile offspring, under the biological species concept. What is natural selection? Natural selection is the process in which organisms with inherited traits that improve survival or reproduction tend to leave more offspring. Who is associated with the theory of evolution by natural selection? Charles Darwin. What is adaptation? An inherited characteristic that helps an organism survive or reproduce in its environment. What is biological fitness? An organism’s ability to survive and reproduce, measured by its contribution of offspring to the next generation. Does the strongest organism always have the highest fitness? No. Fitness depends on how well an organism’s inherited traits help it reproduce in its particular environment. 2. Natural selection What are the main requirements for natural selection? * Individuals in a population have variation. * Some variation is inherited. * Organisms produce more offspring than can survive. * Individuals with certain inherited traits reproduce more successfully. What happens to helpful inherited traits over generations? They may become more common in the population. Can natural selection create traits because organisms need them? No. Natural selection acts on existing inherited variation. It does not create a needed trait simply because an organism needs it. What is an example of natural selection? If insects vary in color and birds more easily spot one color, insects with the less visible color may survive and reproduce more often. Over generations, that color may become more common. 3. Population genetics What is an allele? An alternative version of a gene. What is a gene pool? All the alleles present in a population. What is allele frequency? The proportion of a particular allele in a population. What does it mean when allele frequencies change? The population is evolving. What is genetic variation? Differences in genetic information among individuals in a population. Why is genetic variation important? It provides the differences that natural selection can act on. 4. Mechanisms of evolution What are the five major mechanisms that can change allele frequencies? * Mutation * Gene flow * Genetic drift * Natural selection * Nonrandom mating can change genotype frequencies and, in some circumstances, influence allele frequencies indirectly through selection. What is mutation? A change in DNA sequence. How can mutations affect evolution? They can introduce new genetic variations and sometimes create new alleles. What is gene flow? The movement of alleles between populations when individuals or their reproductive cells move between them. What is genetic drift? A random change in allele frequencies, especially noticeable in small populations. What is the bottleneck effect? A type of genetic drift that happens when a population becomes much smaller due to a random event. What is the founder effect? A type of genetic drift that occurs when a small group separates from a larger population and starts a new population. What is the difference between natural selection and genetic drift? Natural selection is based on differences in reproductive success associated with inherited traits. Genetic drift changes allele frequencies randomly. 5. Hardy-Weinberg equilibrium What is Hardy-Weinberg equilibrium? A model that describes a population that is not evolving with respect to the gene being studied. What are the five Hardy-Weinberg conditions? * No mutations * Random mating * No natural selection * Very large population * No gene flow What is the Hardy-Weinberg equation? p+q=1 What does p represent? The frequency of one allele. What does q represent? The frequency of the other allele. What is the genotype frequency equation? p^2+2pq+q^2=1 What does each part represent? * : Homozygous dominant * : Heterozygous * : Homozygous recessive What does homozygous mean? Having two identical alleles for a gene. What does heterozygous mean? Having two different alleles for a gene. Practice question: If q = 0.4, what is p? Answer: p=1-0.4=0.6 Practice question: If p = 0.6 and q = 0.4, what is the frequency of homozygous dominant individuals? Answer: p^2=0.6^2=0.36 Practice question: If p = 0.6 and q = 0.4, what is the frequency of heterozygous individuals? Answer: 2pq=2(0.6)(0.4)=0.48 Practice question: If p = 0.6 and q = 0.4, what is the frequency of homozygous recessive individuals? Answer: q^2=0.4^2=0.16 6. Evidence for evolution What are some forms of evidence for evolution? * Fossil records * Comparative anatomy * Molecular similarities * Embryology * Biogeography What are fossils? Preserved remains or traces of organisms that lived in the past. What is homologous anatomy? Similar body structures inherited from a common ancestor, even if they serve different functions. What is an example of homologous structures? The forelimbs of humans, whales, bats, and cats. What is analogous anatomy? Structures that perform similar functions but evolved independently and do not come from the same ancestral structure. What is an example of analogous structures? The wings of birds and insects. What is biogeography? The study of where organisms live and how their geographic distribution relates to evolution. How can DNA provide evidence for evolution? Organisms with more similar DNA sequences often share a more recent common ancestor. 7. Speciation What is speciation? The formation of new species. What is reproductive isolation? When populations can no longer successfully reproduce with one another. What is geographic isolation? When physical barriers separate populations, such as mountains, rivers, or oceans. What is allopatric speciation? Speciation that occurs when populations are geographically separated. What is sympatric speciation? Speciation that occurs without geographic separation. Unit 3: Classification, Taxonomy, and Phylogeny 1. Classification What is taxonomy? The science of naming and classifying organisms. What is systematics? The study of biological diversity and evolutionary relationships. What is binomial nomenclature? The two-part scientific naming system for organisms. What are the two parts of a scientific name? Genus and species. How should scientific names be written? The genus is capitalized, the species name is lowercase, and both are italicized. Example: Homo sapiens. What are the main taxonomic levels from broadest to most specific? * Domain * Kingdom * Phylum * Class * Order * Family * Genus * Species What are the three domains of life? * Bacteria * Archaea * Eukarya 2. Phylogenetic trees What is a phylogenetic tree? A diagram showing evolutionary relationships among organisms. What does a branch point represent? A common ancestor where evolutionary lineages split. What is a common ancestor? An ancestral organism or population from which two or more groups evolved. What are sister taxa? Two groups that share an immediate common ancestor. What does a node represent on a phylogenetic tree? A branching point representing a common ancestor. Does being next to another organism on a tree always mean they are closely related? No. Relationships are determined by shared branch points, not simply by how close the names appear. What is a clade? An ancestor and all of its descendants. What is a derived trait? A trait that evolved in a particular lineage and can help identify relationships among organisms. Unit 4: Prokaryotes, Eukaryotes, Bacteria, and Archaea 1. Cell types What are prokaryotic cells? Cells that do not have a nucleus or membrane-bound organelles. What are eukaryotic cells? Cells that have a nucleus and membrane-bound organelles. What organisms are prokaryotes? Bacteria and Archaea. What organisms are eukaryotes? Animals, plants, fungi, and protists. What is the main difference between prokaryotic and eukaryotic cells? Eukaryotic cells have a nucleus and membrane-bound organelles. Prokaryotic cells do not. Where is DNA located in a prokaryotic cell? In a region called the nucleoid. What is the function of the cell membrane? It controls what enters and leaves the cell. What is the function of ribosomes? They make proteins. 2. Bacteria and Archaea What are bacteria? Single-celled prokaryotic organisms found in many environments. What are Archaea? Single-celled prokaryotic organisms that are genetically and chemically distinct from bacteria. What is binary fission? A form of asexual reproduction in which one cell divides into two cells. Do bacteria and archaea have a nucleus? No. What is a bacterial cell wall commonly made of? Peptidoglycan. What is peptidoglycan? A material that provides structure and support to bacterial cell walls. 3. Gram-positive and Gram-negative bacteria What are Gram-positive bacteria? Bacteria with a thick peptidoglycan cell wall that usually stain purple during Gram staining. What are Gram-negative bacteria? Bacteria with a thinner peptidoglycan layer and an outer membrane that usually stain pink or red during Gram staining. What is the major difference between Gram-positive and Gram-negative bacteria? Gram-positive bacteria have thick peptidoglycan walls, while Gram-negative bacteria have thin peptidoglycan walls and an outer membrane. 4. Endosymbiotic theory What is the endosymbiotic theory? The theory that mitochondria and chloroplasts originated from free-living bacteria that were taken into ancestral eukaryotic cells. What organelles are explained by endosymbiotic theory? Mitochondria and chloroplasts. What evidence supports endosymbiotic theory? * They contain their own DNA. * They have their own ribosomes. * They divide in a way similar to bacteria. * They have double membranes. What is the function of mitochondria? They produce most of the cell’s ATP through cellular respiration. What is the function of chloroplasts? They carry out photosynthesis in plants and some other organisms. 5. Protists and fungi What are protists? A diverse group of eukaryotic organisms that do not fit into the traditional plant, animal, or fungi kingdoms. Are all protists single-celled? No. Many are single-celled, but some are multicellular. What are fungi? Eukaryotic organisms that absorb nutrients from their surroundings. What is the cell wall of fungi made of? Chitin. What are examples of fungi? * Mushrooms * Molds * Yeasts How do fungi obtain nutrients? They release digestive enzymes into their surroundings and absorb the broken-down nutrients. What is the role of decomposers? They break down dead organisms and recycle nutrients into the environment. Unit 5: Plants 1. Plant characteristics What are the major characteristics of plants? Plants are multicellular eukaryotes that generally have chloroplasts, cellulose cell walls, and carry out photosynthesis. What is photosynthesis? The process of using light energy to convert carbon dioxide and water into sugars and oxygen. What is the function of chlorophyll? It absorbs light energy for photosynthesis. What is the function of roots? They absorb water and minerals and help anchor the plant. What is the function of stems? They support the plant and transport materials. What is the function of leaves? They are the main organs where photosynthesis occurs in most plants. 2. Alternation of generations What is alternation of generations? A plant life cycle that alternates between two multicellular stages: the haploid gametophyte and the diploid sporophyte. What is a gametophyte? The haploid stage that produces gametes. What is a sporophyte? The diploid stage that produces spores through meiosis. What does haploid mean? Having one set of chromosomes, represented by . What does diploid mean? Having two sets of chromosomes, represented by . What is fertilization? The joining of two gametes to form a diploid zygote. What is meiosis? A type of cell division that reduces the chromosome number by half and produces haploid cells. What is the difference between spores and gametes? Spores can develop into a new organism without fusing with another cell. Gametes must fuse during fertilization to form a zygote. 3. Major plant groups What are the major groups of plants? * Nonvascular plants * Seedless vascular plants * Gymnosperms * Angiosperms What are nonvascular plants? Plants that lack specialized vascular tissues for transporting water and nutrients. What are examples of nonvascular plants? Mosses and liverworts. What are vascular plants? Plants that have specialized tissues to transport water, minerals, and sugars. What are the two major vascular tissues? * Xylem * Phloem What is the function of xylem? It transports water and minerals from the roots toward the rest of the plant. What is the function of phloem? It transports sugars and other organic nutrients throughout the plant. What are seedless vascular plants? Vascular plants that reproduce using spores instead of seeds. What is an example of a seedless vascular plant? Ferns. What are gymnosperms? Seed-producing plants with seeds that are not enclosed within fruits. What is an example of a gymnosperm? Pine trees. What are angiosperms? Flowering plants that produce seeds enclosed within fruits. What is the main difference between gymnosperms and angiosperms? Gymnosperms have exposed seeds, while angiosperms produce seeds enclosed in fruits. 4. Plant reproduction What is pollination? The transfer of pollen from the male reproductive structure to the female reproductive structure of a plant. What is pollen? A structure that carries the male gametophyte in seed plants. What is the purpose of flowers? Flowers are reproductive structures of angiosperms. What develops into a fruit? The ovary of a flower. What develops into a seed? The ovule after fertilization. What is the purpose of seeds? They protect and provide resources for the developing plant embryo. Unit 6: Animals 1. Animal characteristics What are the major characteristics of animals? Animals are multicellular eukaryotes that obtain nutrients by consuming other organisms or organic material. They do not have cell walls. Are animals prokaryotic or eukaryotic? Eukaryotic. Are animals unicellular or multicellular? Multicellular. Are animals autotrophs or heterotrophs? Heterotrophs. What is a heterotroph? An organism that obtains energy and nutrients by consuming other organisms or organic material. 2. Animal body plans What is symmetry? The arrangement of body parts around an axis or center. What is asymmetry? A body shape that cannot be divided into matching halves. What is radial symmetry? A body arrangement in which body parts are organized around a central axis. What is an example of an animal with radial symmetry? A jellyfish. What is bilateral symmetry? A body arrangement that can be divided into approximately equal left and right halves. What is an example of an animal with bilateral symmetry? A human. What is cephalization? The concentration of sensory organs and nervous tissue toward the front or head region of an animal. What is a body cavity? A fluid-filled space within an animal’s body that can contain and protect internal organs. 3. Major animal groups What are sponges? Simple aquatic animals that lack true tissues and organs. What is the scientific phylum for sponges? Porifera. How do sponges obtain food? They filter small food particles from water flowing through their bodies. What are cnidarians? Aquatic animals with specialized stinging cells. What is the scientific phylum for cnidarians? Cnidaria. What are examples of cnidarians? * Jellyfish * Corals * Sea anemones What are cnidocytes? Specialized stinging cells used for capturing prey and defense. What are arthropods? Animals with segmented bodies, jointed appendages, and an external skeleton. What is an exoskeleton? A hard external structure that supports and protects an animal’s body. What are examples of arthropods? * Insects * Spiders * Crabs * Lobsters What is molting? The process of shedding an old exoskeleton so an arthropod can grow. What are the major animal groups covered in this section? * Porifera: Sponges * Cnidaria: Jellyfish, corals, and sea anemones * Arthropoda: Insects, spiders, and crustaceans Note: Your lecture material did not provide a complete list of characteristics for every animal phylum, so I have not added unsupported details to those sections. Unit 7: Biotechnology 1. Biotechnology basics What is biotechnology? The use of living organisms, cells, or biological processes to develop useful products and technologies. What is genetic engineering? The process of directly changing an organism’s DNA. What is recombinant DNA? DNA made by combining genetic material from different sources. What is a plasmid? A small circular DNA molecule commonly found in bacteria. Why are plasmids useful in biotechnology? They can be used to carry selected genes into cells. 2. PCR What does PCR stand for? Polymerase chain reaction. What is PCR used for? To make many copies of a specific DNA segment. What are the three main stages of PCR? * Denaturation * Annealing * Extension What happens during denaturation? The DNA strands separate. What happens during annealing? Primers attach to complementary DNA sequences. What happens during extension? DNA polymerase adds nucleotides to build new DNA strands. 3. Gel electrophoresis What is gel electrophoresis? A laboratory technique used to separate DNA fragments based on size. How does gel electrophoresis separate DNA? An electric current moves DNA fragments through a gel. Smaller fragments generally travel farther than larger fragments. Why does DNA move toward the positive end of the gel? DNA has a negatively charged phosphate backbone. What can gel electrophoresis help scientists do? Compare DNA fragments and examine DNA samples. 4. Restriction enzymes and cloning What are restriction enzymes? Enzymes that cut DNA at specific sequences. What is DNA cloning? The process of making copies of a DNA segment or gene. What is a GMO? A genetically modified organism whose genetic material has been altered using genetic engineering or other genetic modification methods. What is a transgenic organism? An organism that contains genetic material introduced from another species. What is CRISPR? A gene-editing technology that allows scientists to make targeted changes to DNA. What is gene therapy? A medical approach that aims to treat or prevent disease by changing genetic material in a person’s cells. What is genomics? The study of an organism’s entire genome. What is proteomics? The study of the proteins produced by a cell, tissue, or organism. Practice Questions: Multiple Choice The answer is immediately underneath each question. Try answering before reading it. 1. What is the basic building block of DNA? A. Amino acid B. Nucleotide C. Protein D. Lipid Answer: B. Nucleotide 2. Which base pairs with adenine in DNA? A. Guanine B. Cytosine C. Thymine D. Uracil Answer: C. Thymine 3. Which enzyme separates DNA strands during replication? A. Ligase B. Helicase C. RNA polymerase D. Ribosome Answer: B. Helicase 4. What is the purpose of DNA replication? A. To create proteins B. To make RNA C. To copy DNA before cell division D. To destroy old DNA Answer: C. To copy DNA before cell division 5. What is the process of making mRNA from DNA called? A. Translation B. Transcription C. Replication D. Mutation Answer: B. Transcription 6. Where does translation occur? A. Nucleus B. Ribosome C. Cell membrane D. Golgi apparatus Answer: B. Ribosome 7. What does tRNA carry? A. DNA B. Glucose C. Amino acids D. Lipids Answer: C. Amino acids 8. What is the start codon? A. UAA B. AUG C. UGA D. UAG Answer: B. AUG 9. What is evolution? A. An individual changing during its lifetime B. A population changing genetically over generations C. An organism growing larger D. A cell dividing Answer: B. A population changing genetically over generations 10. Who is associated with evolution by natural selection? A. Gregor Mendel B. Charles Darwin C. Louis Pasteur D. Robert Hooke Answer: B. Charles Darwin 11. What is genetic drift? A. A random change in allele frequencies B. The movement of water C. The creation of proteins D. The copying of DNA Answer: A. A random change in allele frequencies 12. What is gene flow? A. DNA replication B. Movement of alleles between populations C. Protein synthesis D. Natural death Answer: B. Movement of alleles between populations 13. Which equation represents Hardy-Weinberg allele frequencies? A. B. C. D. Answer: B. 14. What are the three domains of life? A. Plants, animals, fungi B. Bacteria, Archaea, Eukarya C. Mammals, reptiles, birds D. Protists, fungi, plants Answer: B. Bacteria, Archaea, Eukarya 15. Which cells do not have a nucleus? A. Eukaryotic B. Prokaryotic C. Animal D. Plant Answer: B. Prokaryotic 16. What is the function of mitochondria? A. Protein storage B. ATP production C. DNA protection D. Photosynthesis Answer: B. ATP production 17. What is the cell wall of fungi made of? A. Cellulose B. Peptidoglycan C. Chitin D. Starch Answer: C. Chitin 18. What tissue transports water in plants? A. Phloem B. Xylem C. Epidermis D. Pollen Answer: B. Xylem 19. What is the function of phloem? A. Transport sugars B. Absorb sunlight C. Produce pollen D. Protect seeds Answer: A. Transport sugars 20. Which plants produce flowers? A. Mosses B. Ferns C. Gymnosperms D. Angiosperms Answer: D. Angiosperms 21. What is the scientific phylum for sponges? A. Cnidaria B. Porifera C. Arthropoda D. Chordata Answer: B. Porifera 22. What do arthropods have? A. Jointed appendages and an exoskeleton B. No body structure C. Only soft bodies D. Chloroplasts Answer: A. Jointed appendages and an exoskeleton 23. What is PCR used for? A. Separating proteins B. Copying DNA C. Producing ATP D. Growing plants Answer: B. Copying DNA 24. What does gel electrophoresis separate DNA by? A. Color B. Shape only C. Fragment size D. Temperature Answer: C. Fragment size 25. What is CRISPR used for? A. Editing DNA B. Separating cells C. Making ATP D. Producing pollen Answer: A. Editing DNA Fill-in-the-Blank Practice 1. DNA stands for __________. Answer: Deoxyribonucleic acid. 2. RNA uses __________ instead of thymine. Answer: Uracil. 3. The enzyme that unzips DNA is __________. Answer: Helicase. 4. The enzyme that connects Okazaki fragments is __________. Answer: DNA ligase. 5. The process of making RNA from DNA is called __________. Answer: Transcription. 6. The process of making proteins from mRNA is called __________. Answer: Translation. 7. A group of three mRNA bases is called a __________. Answer: Codon. 8. The movement of alleles between populations is called __________. Answer: Gene flow. 9. Random changes in allele frequencies are called __________. Answer: Genetic drift. 10. The formation of new species is called __________. Answer: Speciation. 11. The three domains are Bacteria, Archaea, and __________. Answer: Eukarya. 12. The cell wall of fungi contains __________. Answer: Chitin. 13. The plant tissue that transports water is __________. Answer: Xylem. 14. The plant tissue that transports sugars is __________. Answer: Phloem. 15. Flowering plants are called __________. Answer: Angiosperms. 16. The haploid plant stage is called the __________. Answer: Gametophyte. 17. The diploid plant stage is called the __________. Answer: Sporophyte. 18. Sponges belong to the phylum __________. Answer: Porifera. 19. Jellyfish belong to the phylum __________. Answer: Cnidaria. 20. The process used to make many copies of DNA is called __________. Answer: PCR. Important Terms to Memorize Term Meaning DNA Stores genetic information RNA Helps make proteins Nucleotide Building block of DNA and RNA Helicase Separates DNA strands DNA polymerase Builds new DNA DNA ligase Connects DNA fragments Transcription DNA to RNA Translation RNA to protein Codon Three mRNA bases Mutation Change in DNA Evolution Change in inherited traits in a population over generations Natural selection Differences in reproductive success based on inherited traits Genetic drift Random allele frequency change Gene flow Movement of alleles between populations Speciation Formation of new species Taxonomy Naming and classifying organisms Phylogeny Evolutionary relationships Prokaryote Cell without a nucleus Eukaryote Cell with a nucleus Mitochondria ATP production Chloroplast Photosynthesis Xylem Transports water Phloem Transports sugars Gametophyte Haploid plant generation Sporophyte Diploid plant generation Angiosperm Flowering plant Gymnosperm Plant with exposed seeds PCR Makes copies of DNA Gel electrophoresis Separates DNA fragments by size CRISPR Gene-editing technology Final Cram Sheet: What You Should Know Before Your Exam DNA and genetics * DNA: A–T and C–G * RNA: A–U and C–G * Helicase: unzips DNA * DNA polymerase: builds DNA * Ligase: joins DNA fragments * Transcription: DNA → RNA * Translation: RNA → protein * AUG: start codon * UAA, UAG, UGA: stop codons Evolution * Darwin: natural selection * Mutation: changes DNA * Genetic drift: random change * Gene flow: movement between populations * Bottleneck: population becomes much smaller * Founder effect: small group starts a population * Speciation: new species form * Hardy-Weinberg: , Classification and cells * Three domains: Bacteria, Archaea, Eukarya * Prokaryotes: no nucleus * Eukaryotes: have a nucleus * Mitochondria: ATP * Chloroplasts: photosynthesis * Fungi: chitin cell walls * Bacteria: peptidoglycan cell walls Plants * Xylem: water * Phloem: sugar * Gametophyte: haploid * Sporophyte: diploid * Gymnosperms: exposed seeds * Angiosperms: flowers and enclosed seeds * Mosses: nonvascular * Ferns: seedless vascular Animals and biotechnology * Porifera: sponges * Cnidaria: jellyfish, corals, sea anemones * Arthropoda: jointed appendages and exoskeleton * PCR: copies DNA * Gel electrophoresis: separates DNA by size * Restriction enzymes: cut DNA * CRISPR: edits DNA Study tip: Cover the answers with a piece of paper and try to answer every question from memory. Then uncover the answer and check yourself. Focus especially on DNA replication, transcription versus translation, Hardy-Weinberg equations, evolution mechanisms, plant life cycles, and the differences between prokaryotic and eukaryotic cells.

BTEC Level 3 Applied Science – COMPLETE Biology Revision Pack This is your main revision guide based on all the B1, B2 and B3 notes you shared and everything we’ve been practising. It includes: * All the main topics you need to revise. * Definitions and key scientific terms. * Cell structures and their functions. * Specialised cells and immunity. * Tissues, lungs and circulation. * Muscles and the nervous system. * ECGs. * 6-mark practice questions. * Mnemonics with every letter explained. * Exam-ready answers. Important: Nobody can guarantee the exact questions that will come up. This covers the topics in your notes, including likely extended-answer areas. Use your official unit specification and teacher’s guidance alongside it. PART 1 – B1: CELL STRUCTURE 1. Levels of organisation Learn these definitions: Term Definition Cell Basic structural and functional unit of life. Tissue Group of similar specialised cells working together. Organ Different tissues working together to perform a function. Organ system Different organs working together. Organelle Specialised structure inside a cell. Mnemonic: Cats Take Over Sofas * Cats = Cells * Take = Tissues * Over = Organs * Sofas = Systems Order: Cell → Tissue → Organ → Organ system. 2. Differentiation Definition: Differentiation is when an unspecialised cell develops into a specialised cell to perform a particular function. Examples: * A stem cell can become a red blood cell. * A stem cell can become a neurone. * A stem cell can become a muscle cell. 3. Prokaryotic cells Prokaryotes are cells without a nucleus. Learn these structures: Structure Function Nucleoid Contains circular DNA. Plasmids Small extra rings of DNA. 70S ribosomes Protein synthesis. Capsule Protection and attachment. Cell wall Made of peptidoglycan; provides support. Cell membrane Controls substances entering and leaving. Cytoplasm Where chemical reactions occur. Mnemonic: Naughty Pigs Rarely Chase Wolves * N = Nucleoid * P = Plasmids * R = Ribosomes * C = Capsule * W = Wall Remember: Prokaryotes do not have a nucleus or membrane-bound organelles. 4. Eukaryotic cells Eukaryotic cells have: * A nucleus. * 80S ribosomes in the cytoplasm. * Membrane-bound organelles. Plant cells Structure Function Cellulose cell wall Support and protection. Chloroplasts Photosynthesis. Permanent vacuole Contains cell sap and helps maintain turgor. Tonoplast Membrane surrounding the vacuole. Amyloplasts Store starch. Plasmodesmata Connections between neighbouring plant cells. Pits Areas where the cell wall is thinner. Animal cells Animal cells can contain: * Nucleus. * Mitochondria. * Ribosomes. * Cell membrane. * Cytoplasm. * Centrioles. * Glycogen stores. Animal cells do not have cellulose cell walls or chloroplasts. 5. Organelles and their functions Organelle Function Cell membrane Controls movement of substances. Cytoplasm Site of many chemical reactions. Nucleus Contains DNA and controls cell activities. Nucleolus Produces ribosomal components. Ribosomes Protein synthesis. Rough ER Transports and processes proteins. Smooth ER Lipid and steroid synthesis. Golgi apparatus Modifies, sorts and packages proteins. Vesicles Transport substances. Lysosomes Contain digestive enzymes. Mitochondria Aerobic respiration and ATP production. Centrioles Help organise spindle fibres during cell division. Chloroplasts Photosynthesis. Identifying organelles in micrographs * Mitochondria: oval shape with folded inner membranes called cristae. * Nucleus: large structure with a double membrane and pores. * Rough ER: flattened membranes with ribosomes attached. * Chloroplast: contains stacks of membranes called grana. * Golgi: curved, flattened membrane sacs. * Bacteria: no nucleus; DNA lies free in the cytoplasm. 6. Light and electron microscopes Light microscope Electron microscope Uses light. Uses an electron beam. Lower resolution. Higher resolution. Lower magnification. Higher magnification. Can view living cells. Specimens must be dead. Can show natural colours. Original images are monochrome. Generally cheaper. Generally more expensive. Mnemonic: M R C L * M = Magnification * R = Resolution * C = Colour * L = Living specimens 7. Magnification calculations Learn these three formulas: M=\frac{I}{A}I=M\times AA=\frac{I}{M} Where: * M = Magnification * I = Image size * A = Actual size Conversions: * 1 mm = 1000 µm * 1 µm = 1000 nm Always make sure your measurements use the same units. Stage micrometer and eyepiece graticule A graticule is calibrated against a stage micrometer. Mnemonic: Lazy Chefs Dice Meat * L = Line up the scales. * C = Count the divisions. * D = Divide the known measurement by the number of divisions. * M = Measure the specimen. Recalibrate when changing magnification. PART 2 – GRAM STAINING AND ANTIBIOTICS 8. Gram-positive and Gram-negative bacteria Gram-positive Gram-negative Thick peptidoglycan wall. Thin peptidoglycan wall. No outer membrane. Has an outer membrane. Stains purple. Stains pink/red. Generally more susceptible to penicillin. Outer membrane provides additional protection. 9. Gram staining Mnemonic: Hot Cats In Autumn Spring * Hot = Heat-fix: Fix bacteria onto a microscope slide. * Cats = Crystal violet: Add purple dye. * In = Iodine: Helps retain the crystal violet. * Autumn = Alcohol: Removes the dye from Gram-negative bacteria. * Spring = Safranin: Counterstains Gram-negative bacteria pink. * Result: Gram-positive purple, Gram-negative pink/red. 10. Penicillin Penicillin prevents the formation of cross-links in bacterial peptidoglycan. This: * Weakens the bacterial cell wall. * Allows water to enter by osmosis. * Causes the bacterial cell to burst (lysis). Gram-positive bacteria are generally more susceptible because their peptidoglycan is more accessible. Gram-negative bacteria have an outer membrane that can prevent or reduce penicillin entry. PART 3 – B2: SPECIALISED CELLS 11. Palisade cells Adaptations: * Contain many chloroplasts for photosynthesis. * Tall, thin shape allows cells to be closely packed. * Found near the upper surface of leaves to receive light. * Large vacuole pushes chloroplasts towards the cell edge. * Thin cell wall helps carbon dioxide diffuse into the cell. 12. Sperm cells Mnemonic: A Happy Mouse Tails * A = Acrosome: Contains enzymes to digest the egg’s outer layers. * H = Haploid nucleus: Contains half the normal chromosome number. * M = Mitochondria: Produce ATP for movement. * T = Tail: Flagellum propels the sperm. * S = Streamlined: Helps movement through fluid. 13. Egg cells Adaptations: * Large cytoplasm containing nutrient reserves. * Haploid nucleus. * Zona pellucida surrounds the egg. * Cortical granules help prevent polyspermy after fertilisation. Polyspermy: When more than one sperm fertilises an egg. 14. Root hair cells Adaptations: * Long extension gives a large surface area. * Thin cell wall gives a short diffusion distance. * Cell sap helps water enter by osmosis. * Mitochondria supply ATP for active transport of mineral ions. 15. Red blood cells Adaptations: * Biconcave shape gives a large surface area. * No nucleus, leaving more room for haemoglobin. * Haemoglobin binds oxygen. * Flexible shape allows movement through narrow capillaries. * Thin centre gives a short diffusion distance. Oxygen + haemoglobin ⇌ oxyhaemoglobin. 16. White blood cells Two important types: Neutrophils * Have a lobed nucleus. * Engulf pathogens by phagocytosis. * Use lysosomes containing digestive enzymes. * Form part of the innate immune response. * Respond rapidly to infection. Lymphocytes * Have a large, round nucleus. * B lymphocytes can develop into plasma cells. * Plasma cells produce specific antibodies. * Some become memory cells. * T lymphocytes can destroy infected cells. 17. Neutrophils and lymphocytes: similarities and differences Similarities mnemonic: Both Need Protection * Both = Both are white blood cells. * Need = Both contain a nucleus. * Protection = Both protect against pathogens. Differences: Neutrophils Lymphocytes Phagocytosis. Specific immune response. Lobed nucleus. Large, round nucleus. Digest pathogens using lysosomes. B cells produce antibodies. Part of innate immunity. Part of adaptive immunity. Respond rapidly. Can form long-lasting memory cells. 18. Antibodies and immunity Learn: * An antigen is a molecule recognised by the immune system. * Antibodies have binding sites complementary to specific antigens. * Antibodies bind to antigens. * This can neutralise pathogens or help other immune cells destroy them. * B lymphocytes can form memory cells. * Memory cells help produce a faster secondary response. 19. Allergies Mnemonic: A M H * A = Allergen enters the body. * M = Mast cells become involved. * H = Histamine is released. Histamine causes: * Blood vessels to widen. * Capillaries to become more permeable. * Fluid to move into tissues. * Swelling, itching and other allergic symptoms. 20. Transplant rejection Learn this sequence: * Donor cells have antigens. * The recipient recognises these antigens as foreign. * T lymphocytes recognise the foreign cells. * T cells attack the transplanted tissue. * Tissue matching reduces the chance of rejection. * Immunosuppressants reduce immune activity. PART 4 – B3: TISSUES AND THE RESPIRATORY SYSTEM 21. Epithelial tissues Squamous epithelium * Thin, flat cells. * Usually one cell thick in diffusion surfaces. * Short diffusion distance. * Found in alveoli and capillary walls. Columnar epithelium * Tall cells. * Can contain goblet cells. * Ciliated columnar cells move mucus. * Microvilli in the gut increase surface area for absorption. Endothelium * Lines the inside of blood vessels. * Smooth surface reduces friction. * Thin capillary endothelium allows diffusion. 22. COPD COPD stands for chronic obstructive pulmonary disease. Two important conditions: Emphysema Mnemonic: Smoking Makes Every Alveolus Lose Elasticity * Smoking causes inflammation. * White blood cells release elastase. * Elastase destroys alveolar walls. * Alveoli merge into larger air spaces. * Surface area decreases. * Elastic recoil decreases, causing difficulty breathing out. Chronic bronchitis Mnemonic: Irritated Goblets Make Coughing Increase * I = Inflammation of the bronchi. * G = Goblet cells enlarge. * M = More mucus is produced. * C = Cilia become damaged. * I = Infections become more common. * B = Bronchi narrow, causing coughing and breathing difficulties. 23. Alveoli adaptations Mnemonic: Silly Tigers Carry Very Massive Eggs * S = Surface area: Millions of alveoli create a large surface area. * T = Thin walls: One cell thick, short diffusion distance. * C = Capillaries: Dense network maintains the concentration gradient. * V = Ventilation: Refreshes alveolar air. * M = Moisture: Gases dissolve in the lining. * E = Elasticity: Allows stretching and recoil. 24. Gas exchange Oxygen moves: Alveolar air → Alveolar epithelium → Basement membrane → Capillary endothelium → Plasma → Red blood cell → Haemoglobin. Carbon dioxide moves in the opposite direction. Fick’s law Diffusion is faster when: * Surface area is larger. * Diffusion distance is shorter. * Concentration gradient is steeper. 25. Breathing and inhalation Mnemonic: Dancing Rabbits Visit Pretty Amazing Places * D = Diaphragm contracts and flattens. * R = Ribs move upwards and outwards. * V = Thoracic volume increases. * P = Pressure inside lungs decreases. * A = Air moves into the lungs. * P = Pressure equalises as air enters. Exhalation * Diaphragm relaxes and becomes dome-shaped. * External intercostal muscles relax. * Ribs move downwards and inwards. * Thoracic volume decreases. * Pressure inside the lungs increases. * Air moves out. 26. Smoking effects Mnemonic: Cigarettes Make Every Lung Suffer * C = Cilia damaged. * M = More mucus produced. * E = Excess infections. * L = Loss of alveolar walls. * S = Surface area reduced. * S = Smoking reduces lung elasticity. Smoking also damages blood vessel endothelium and increases atherosclerosis risk. PART 5 – ATHEROSCLEROSIS AND CIRCULATION 27. Atherosclerosis High-priority 6-marker Mnemonic: Dirty Money’s Find Pipes Narrowing Today * Dirty = Damage: The endothelium lining the artery becomes damaged. * Money’s = Macrophages: Macrophages enter the artery wall and engulf LDL cholesterol. * Find = Foam cells: Macrophages become foam cells, forming fatty streaks. * Pipes = Plaque: Fatty material builds up and forms a plaque. * Narrowing = Narrowing: The plaque narrows the artery and reduces blood flow. * Today = Thrombus: A blood clot can form and block the artery, potentially causing a heart attack or stroke. Risk factors * Smoking. * High blood pressure. * High LDL cholesterol. * Diabetes. * Age. * Poor diet. PART 6 – MUSCLES 28. Skeletal muscle structure Learn these terms: Structure Function Sarcolemma Muscle fibre cell membrane. Sarcoplasm Muscle fibre cytoplasm. Myofibrils Contain actin and myosin. Sarcomere Contractile unit between Z lines. Actin Thin filament. Myosin Thick filament. Sarcoplasmic reticulum Stores and releases calcium ions. Mitochondria Produce ATP. Skeletal muscle fibres are: * Long and cylindrical. * Multinucleate. * Striated. * Packed with myofibrils. 29. Sarcomere changes Structure During contraction A band Stays the same length. I band Shortens. H zone Shortens. Z lines Move closer together. Sarcomere Shortens. Mnemonic: A stays Always the same; I and H get Hit. 30. Sliding filament theory High-priority 6-marker Mnemonic: Clever Tigers Make Powerful Animals Run * Clever = Calcium: Calcium is released from the sarcoplasmic reticulum. * Tigers = Troponin: Calcium binds to troponin, moving tropomyosin. * Make = Myosin: Myosin binds to actin, forming cross-bridges. * Powerful = Power stroke: Myosin pulls actin towards the centre of the sarcomere. * Animals = ATP: ATP binds to myosin, causing detachment. * Run = Reset: ATP is broken down, re-cocking the myosin head. Remember: Actin and myosin do not shorten; they slide past one another. 31. Slow-twitch and fast-twitch fibres Mnemonic: Slow Red Runners Have Endurance Slow-twitch Type I * Red. * Lots of myoglobin. * Many mitochondria. * Dense capillary supply. * Mainly aerobic respiration. * Resist fatigue. * Used for endurance activities such as marathons. Fast-twitch Type II * Paler. * Less myoglobin. * Fewer mitochondria. * Lower capillary density. * More reliance on anaerobic energy pathways. * Contract quickly and powerfully. * Fatigue more quickly. * Used for sprinting and weightlifting. Remember: Slow = Stamina. Fast = Force. PART 7 – NERVOUS SYSTEM 32. Motor neurone structure Mnemonic: Dogs Can Always Nip Toes * D = Dendrites receive signals. * C = Cell body contains nucleus. * A = Axon carries the impulse. * N = Nodes of Ranvier are gaps in myelin. * T = Terminals release neurotransmitters. Myelin sheath * Insulates the axon. * Increases conduction speed. * Schwann cells produce myelin in the peripheral nervous system. * Nodes of Ranvier allow saltatory conduction. 33. Resting potential Mnemonic: Three Naughty Cats Keep Purring Inside * Three = 3 sodium ions pumped out. * Naughty = 2 potassium ions pumped in. * Cats = Pump uses ATP. * Keep = Potassium ions leak out. * Purring = Negative proteins remain inside. * Inside = Inside becomes approximately −70 mV. 34. Action potential Mnemonic: Silly Dogs Run Happily Past Houses * S = Stimulus reaches threshold (−55 mV). * D = Depolarisation begins as sodium channels open. * R = Rising potential as sodium enters. * H = High positive potential, around +40 mV. * P = Potassium channels open and potassium leaves. * H = Hyperpolarisation before returning to resting potential. Important extra facts * Action potentials are all-or-nothing. * A stronger stimulus increases frequency, not the size of the action potential. * The refractory period prevents immediate re-firing. * It helps ensure impulses travel in one direction. 35. Myelinated and non-myelinated neurones Mnemonic: Myelin Jumps Fast * Myelinated neurones have a myelin sheath. * They have nodes of Ranvier. * Impulses jump from node to node. * This is called saltatory conduction. * Non-myelinated neurones conduct continuously. * Myelinated neurones are faster and generally use less energy for impulse transmission. 36. Synaptic transmission High-priority 6-marker Mnemonic: All Clever Vikings Drink Really Slowly * All = Action potential: Arrives at the presynaptic knob. * Clever = Calcium: Calcium channels open and calcium enters. * Vikings = Vesicles: Vesicles release neurotransmitter by exocytosis. * Drink = Diffusion: Neurotransmitter diffuses across the synaptic cleft. * Really = Receptors: Neurotransmitter binds to postsynaptic receptors. * Slowly = Sodium: Sodium channels open and sodium enters, causing depolarisation. Extra: * Neurotransmitter is removed by enzymes or reuptake. * Synapses are one-way because receptors are on the postsynaptic membrane. 37. Acetylcholine Mnemonic: Release, Bind, Sodium, Enzyme, Recycle * Release: Acetylcholine is released from vesicles. * Bind: It binds to postsynaptic receptors. * Sodium: Sodium channels open. * Depolarisation: The membrane becomes less negative. * Enzyme: Acetylcholinesterase breaks down acetylcholine. * Recycle: Choline is taken back into the presynaptic neurone. 38. Agonists and antagonists Mnemonic: Agonist Activates; Antagonist Blocks. * Agonist binds to a receptor and activates it. * It can mimic a natural neurotransmitter. * Antagonist binds without activating the receptor. * It blocks the natural neurotransmitter from binding. Examples: * Nicotine: agonist at certain acetylcholine receptors. * Curare: antagonist at acetylcholine receptors. Other examples to know: * L-dopa is converted into dopamine. * SSRIs block serotonin reuptake. * Botulinum toxin prevents acetylcholine release. * Organophosphates inhibit acetylcholinesterase. 39. Neurotransmitters Neurotransmitter Main role Acetylcholine Muscle contraction and signalling. Glutamate Main excitatory neurotransmitter in the brain. GABA Main inhibitory neurotransmitter in the brain. Dopamine Movement and reward. Serotonin Mood, sleep and appetite. Noradrenaline Alertness and attention. 40. Parkinson’s disease Mnemonic: Dying Dopamine Makes Movement Slow * Dopamine-producing neurones in the substantia nigra degenerate. * Less dopamine is released. * Movement control is disrupted. * Symptoms include tremors, rigidity and slow movement. * L-dopa can be converted into dopamine in the brain. * Dopamine agonists can also help manage symptoms. 41. Depression and SSRIs Mnemonic: Serotonin Reuptake is Controlled, Levels Last * Serotonin is involved in mood regulation. * Serotonin is released into the synaptic cleft. * Normally, some serotonin is taken back into the presynaptic neurone. * SSRIs block serotonin reuptake transporters. * Serotonin remains in the synaptic cleft longer. * It can continue binding to postsynaptic receptors. PART 8 – ECGs 42. ECG waves Mnemonic: Please Quit Rushing, Stay Tranquil * P wave: Atrial depolarisation. * QRS complex: Ventricular depolarisation. * T wave: Ventricular repolarisation. Remember: * Atrial depolarisation is followed by atrial contraction. * Ventricular depolarisation is followed by ventricular contraction. * Ventricular repolarisation is followed by ventricular relaxation. 43. Heart rate calculations \text{Heart rate}=\frac{60}{\text{R-R interval in seconds}} Example: If the R-R interval is 0.8 seconds: 60\div0.8=75\text{ bpm} Know: * Tachycardia: over 100 beats per minute. * Bradycardia: under 60 beats per minute. * Regular R-R intervals indicate a regular rhythm. PART 9 – ALL THE 6-MARK QUESTIONS TO PRACTISE These are the extended-answer questions I would use to test your knowledge. They are based on your notes, not guaranteed predictions. Your 30-question exam checklist Tick each question once you can answer it without notes. 0/30 All 1. B1 – CellsCompare prokaryotic and eukaryotic cells. (6 marks) 2. B1 – CellsCompare light and electron microscopes. (6 marks) 3. B1 – MicroscopyExplain how to calculate magnification and actual size. (6 marks) 4. B1 – Gram stainingDescribe how Gram staining is carried out and how it identifies bacteria. (6 marks) 5. B1 – AntibioticsExplain why penicillin is generally more effective against Gram-positive bacteria. (6 marks) 6. B2 – Specialised cellsExplain how a sperm cell is adapted for fertilisation. (6 marks) 7. B2 – Specialised cellsExplain how a red blood cell is adapted to transport oxygen. (6 marks) 8. B2 – ImmunityExplain how phagocytes destroy pathogens. (6 marks) 9. B2 – ImmunityExplain how lymphocytes defend the body against pathogens. (6 marks) 10. B2 – ImmunityCompare the similarities and differences between neutrophils and lymphocytes. (6 marks) 11. B2 – ImmunityExplain how allergies occur. (6 marks) 12. B2 – ImmunityExplain how organ transplants can be rejected. (6 marks) 13. B3 – TissuesExplain how atherosclerosis develops. (6 marks) 14. B3 – LungsExplain how emphysema affects gas exchange. (6 marks) 15. B3 – LungsExplain how chronic bronchitis develops. (6 marks) 16. B3 – LungsExplain how alveoli are adapted for gas exchange. (6 marks) 17. B3 – LungsExplain the mechanism of inhalation. (6 marks) 18. B3 – LungsExplain how smoking damages the respiratory system. (6 marks) 19. MusclesExplain the sliding filament mechanism of muscle contraction. (6 marks) 20. MusclesCompare slow-twitch and fast-twitch muscle fibres. (6 marks) 21. NervesExplain how resting potential is maintained. (6 marks) 22. NervesExplain how an action potential is generated. (6 marks) 23. NervesCompare myelinated and non-myelinated neurones. (6 marks) 24. NervesExplain how an impulse travels along a myelinated neurone. (6 marks) 25. NervesExplain how a synapse transmits a nerve impulse. (6 marks) 26. NervesExplain how acetylcholine works at a synapse. (6 marks) 27. NervesExplain the difference between agonists and antagonists. (6 marks) 28. NervesExplain how Parkinson’s disease affects the nervous system. (6 marks) 29. NervesExplain how SSRIs affect synaptic transmission. (6 marks) 30. ECGsExplain what the P wave, QRS complex and T wave represent. (6 marks) Reset checklist PART 10 – IMPORTANT DEFINITIONS TO MEMORISE Term Meaning Diffusion Net movement of particles from high to low concentration. Osmosis Net movement of water across a partially permeable membrane from higher to lower water potential. Active transport Movement against a concentration gradient using energy. Phagocytosis Engulfing and digesting pathogens. Antigen Molecule recognised by the immune system. Antibody Protein that binds to a specific antigen. Depolarisation Membrane potential becomes less negative. Repolarisation Membrane potential returns towards its resting value. Hyperpolarisation Membrane potential becomes more negative than resting potential. Synapse Junction between neurones where signals are transmitted. Neurotransmitter Chemical messenger released at a synapse. Exocytosis Release of substances when vesicles fuse with a cell membrane. Atheroma Fatty plaque in an artery wall. Thrombus Blood clot formed within a blood vessel. Sarcomere Contractile unit of a myofibril. Oxyhaemoglobin Haemoglobin bound to oxygen. COPD Chronic obstructive pulmonary disease. Differentiation Process by which cells become specialised. PART 11 – THE MOST IMPORTANT MNEMONICS TO KNOW Here is your quick podcast-style recap. Read these aloud every day. Topic Mnemonic Cell organisation Cats Take Over Sofas Prokaryotic structures Naughty Pigs Rarely Chase Wolves Graticule calibration Lazy Chefs Dice Meat Gram staining Hot Cats In Autumn Spring Sperm cell A Happy Mouse Tails Atherosclerosis Dirty Money’s Find Pipes Narrowing Today Neutrophil and lymphocyte similarities Both Need Protection Alveoli Silly Tigers Carry Very Massive Eggs Inhalation Dancing Rabbits Visit Pretty Amazing Places Chronic bronchitis Irritated Goblets Make Coughing Increase Emphysema Smoking Makes Every Alveolus Lose Elasticity Sliding filament Clever Tigers Make Powerful Animals Run Slow-twitch fibres Slow Red Runners Have Endurance Motor neurone Dogs Can Always Nip Toes Action potential Silly Dogs Run Happily Past Houses Resting potential Three Naughty Cats Keep Purring Inside Synapse All Clever Vikings Drink Really Slowly Parkinson’s Dying Dopamine Makes Movement Slow ECG Please Quit Rushing, Stay Tranquil PART 12 – HOW TO REVISE THIS FOR YOUR EXAM I would revise in this order: Your 7-day revision plan * Day 1 – Cells Cell structures, prokaryotes, eukaryotes, microscopes and magnification. * Day 2 – Specialised cells Sperm, egg, root hair, palisade and red blood cells. * Day 3 – Immunity Neutrophils, lymphocytes, antibodies, allergies and transplant rejection. * Day 4 – Lungs and circulation Alveoli, inhalation, COPD, smoking and atherosclerosis. * Day 5 – Muscles Sarcomeres, sliding filament theory and muscle fibre comparisons. * Day 6 – Nervous system Resting potential, action potentials, synapses, neurotransmitters and Parkinson’s. * Day 7 – Exam practice Attempt the 6-mark questions without notes, then check your answers. My final advice For every 6-marker, learn: * The mnemonic. * What every letter stands for. * The scientific explanation. * The correct order of events. You have already shown that you can remember the atherosclerosis sequence and explain it in your own words. That’s exactly how you should practise the rest. Don’t just memorise the mnemonics. Make sure you understand what each biological process actually means. That’s what will help you answer the question even if the examiner words it differently.

bac phys exam 2- peptidoglycan synthesis

Learn: Bacterial Cell Structure, Peptidoglycan, and Antibiotic Targets

Microbiology — Important Test Questions 1. What are microorganisms? Organisms too small to be seen with the unaided eye/ Human eye. 2. What are the major types of microbes? Bacteria, archaea, fungi, protozoa, algae, and viruses. 3. Are all microbes harmful? No. Most are helpful or harmless; only some are pathogenic. (Disease causing) 4. What are some important benefits of microbes? They decompose waste, produce oxygen, make foods and chemicals, and produce useful products such as insulin. (Medicine) Naming Microorganisms 5. What are the two parts of a scientific name? Genus and specific epithet. 6. How are scientific names written? The genus is capitalized, the specific epithet is lowercase, and both are italicized or underlined. 7. How is a scientific name abbreviated? The genus is shortened to its first letter. Example: Escherichia coli → E. coli. Bacteria -single cell 8. Are bacteria prokaryotic or eukaryotic? Prokaryotic. 9. Do bacteria have a nucleus? No. 10. What is found in bacterial cell walls? Peptidoglycan cell wall 11. How do bacteria reproduce? Binary fission. 12. How can bacteria obtain nutrition? From organic chemicals, inorganic chemicals, or photosynthesis. Archaea- single cell 13. Are archaea prokaryotic or eukaryotic? Prokaryotic. 14. Do archaea have peptidoglycan in their cell walls? No. 15. Where are many archaea found?c Extreme environments. 16. What are the three major groups of archaea mentioned? Methanogens, extreme halophiles, and extreme thermophiles. Fungi - can be mult 17. Are fungi prokaryotic or eukaryotic? Eukaryotic. 18. What is found in fungal cell walls? Chitin. 19. How do fungi obtain energy? They absorb organic chemicals. 20. What is the difference between yeast and molds? Yeasts are unicellular; molds are multicellular. 21. What are hyphae? Filaments that make up fungal mycelia. Protozoa- single cell 22. Are protozoa prokaryotic or eukaryotic? Eukaryotic. 23. How do protozoa obtain nutrients? They absorb or ingest organic chemicals. 24. How can protozoa move? Using pseudopods, cilia, or flagella. 25. Can protozoa be parasitic? Yes. Algae -can be mult 26. Are algae prokaryotic or eukaryotic? Eukaryotic. 27. What is found in algal cell walls? Cellulose. 28. How do algae obtain energy? Photosynthesis. 29. What do algae produce through photosynthesis? Oxygen and carbohydrates. Viruses- not living 30. Are viruses cellular? No. They are acellular. 31. What genetic material do viruses contain? DNA or RNA. 32. What surrounds the viral genetic material? A protein coat. 33. Can viruses reproduce on their own? No. They replicate only inside living host cells. Can only be seen in microsocp 34. What are viruses like outside a living host cell? They are inert. Classification 35. What are the three domains? Bacteria, Archaea, and Eukarya. 36. Who developed the three-domain system? Carl Woese. History of Microbiology 37. Who first observed microorganisms? Anton van Leeuwenhoek. 38. Who helped establish the idea that living things are made of cells? Robert Hooke. 39. What is cell theory? All living things are composed of cells. Pasteur & Fermentation 40. What did Pasteur show about fermentation? Microorganisms are responsible for fermentation. 41. What is fermentation? The microbial conversion of sugar to alcohol in the absence of air. 42. What is pasteurization? Using high heat for a short time to kill harmful bacteria in beverages. 43. Why is pasteurization important? It helps prevent microbial spoilage and kills harmful bacteria. Major Fields 47. What is bacteriology? Study of bacteria. 48. What is mycology? Study of fungi. 49. What is parasitology? Study of protozoa and parasitic worms. 50. What is immunology? Study of immunity. 51. What is virology? Study of viruses. Penicillin 44. Who discovered penicillin? Alexander Fleming. 45. What organism produced penicillin? The fungus Penicillium. 46. What type of microorganism did penicillin kill in Fleming's observation? Staphylococcus aureus bacteria. Genetics & Biotechnology 52. What is microbial genetics? Study of how microbes inherit traits. 53. What is molecular biology? How DNA directs protein synthesis. 54. What is genomics? Study of an organism's genes. 55. What is recombinant DNA? . DNA made from two different sources. 56. What is gene therapy? Replacing missing or defective genes in human cells Microbial Ecology & Biotechnology 57. What is microbial ecology? Study of the relationship between microorganisms and their environment. 58. What is bioremediation? Using microorganisms to clean up or detoxify pollutants. 59. How can bacteria help the environment? They can break down sewage and pollutants such as oil. 60. What is biotechnology? Using microorganisms for practical purposes, such as producing foods, chemicals, proteins, vaccines, and enzymes. Microbiota & Biofilms 61. What is microbiota? The microorganisms normally present in or on the body. 62. What is a biofilm? A mass of microorganisms attached to a solid surface. 63. Why are biofilms important medically? They can cause infections and are often resistant to antibiotics. 64. What does “pathogenic” mean? Disease-producing; capable of causing disease. 65. What is binary fission? A process in which one bacterial cell divides into two cells. 71. What did Anton van Leeuwenhoek call the microorganisms he observed? “Animalcules.” 74. Why is Bacillus thuringiensis useful in agriculture? It kills many harmful insects but is harmless to animals and plants, making it an alternative to chemical pesticides. All microorganisms that regularly populate the human body are referred to as the human microbiome

bio Genetics is the study of heredity and how traits are passed from parents to offspring. Gregor Mendel is known as the “Father of Genetics.” Why did Mendel use pea plants? * Easy to grow * Short generation time * Many visible traits * Can self-pollinate or cross-pollinate * Produce many offspring Examples of traits studied: * Flower colour * Seed shape * Plant height ⸻ VOCABULARY Gene * A segment of DNA that controls a trait. Allele * Different forms of the same gene. Example: P = purple flowers p = white flowers Dominant Allele * Expressed whenever it is present. * Represented by a capital letter. Example: P = purple Recessive Allele * Only expressed when two copies are present. * Represented by a lowercase letter. Example: p = white Genotype * Genetic makeup of an organism. Examples: PP Pp pp Phenotype * Physical appearance of an organism. Examples: Purple flower White flower Homozygous * Two identical alleles. Examples: PP pp Heterozygous * Two different alleles. Example: Pp Pure Breeding * Homozygous for a trait. Gamete * Sex cell (sperm or egg). ⸻ MENDEL’S LAWS Law of Dominance * A dominant allele masks a recessive allele. Example: Pp = Purple flower Law of Segregation * Alleles separate during gamete formation. * Each gamete receives only one allele. Example: Parent = Pp Gametes: P p Law of Independent Assortment * Different genes assort independently during meiosis. ⸻ MONOHYBRID CROSSES A monohybrid cross studies one trait. Example: P = Purple p = White Cross: Pp × Pp Punnett Square INCOMPLETE DOMINANCE Neither allele completely dominates. Example: Snapdragons RR = Red WW = White RW = Pink Cross: RW × RW Genotype Ratio: 1 RR : 2 RW : 1 WW Phenotype Ratio: 1 Red : 2 Pink : 1 White CODOMINANCE Both alleles are expressed equally. Example: AB Blood Type Genotype: IAIB Phenotype: AB MULTIPLE ALLELES More than two alleles exist in a population. Example: ABO Blood Group Alleles: IA IB i BLOOD TYPES Type A Genotypes: IAIA or IAi Type B Genotypes: IBIB or IBi Type AB Genotype: IAIB Type O Genotype: ii Can Type A and Type B Parents Have a Type O Child? Yes. If: Father = IAi Mother = IBi Possible Blood Types: AB A B O CELL CYCLE Purpose: * Growth * Repair * Replacement of cells Stages: G1 S G2 Mitosis Cytokinesis INTERPHASE G1 Phase Cell grows and carries out normal functions. S Phase DNA replication occurs. G2 Phase Cell prepares for division. MITOSIS Purpose: Growth and repair. Produces: 2 genetically identical diploid cells. PROPHASE Events: * Chromosomes condense * Nuclear membrane disappears * Nucleolus disappears * Spindle fibres form METAPHASE Events: * Chromosomes line up at the equator ANAPHASE Events: * Sister chromatids separate TELOPHASE Events: * Nuclear membranes reform * Chromosomes uncoil CYTOKINESIS Division of the cytoplasm. Animal Cells: Cleavage furrow forms. Plant Cells: Cell plate forms. CHROMOSOME STRUCTURE Chromosome consists of: * Two sister chromatids * One centromere DIPLOID VS HAPLOID Diploid (2n) * Two sets of chromosomes * Human body cells * 46 chromosomes Haploid (n) * One set of chromosomes * Human gametes * 23 chromosomes HOMOLOGOUS CHROMOSOMES Chromosome pairs that: * Carry the same genes * One comes from the mother * One comes from the father Humans have 23 homologous pairs. MEIOSIS Purpose: Produce gametes. Produces: 4 genetically unique haploid cells. MEIOSIS I Separates homologous chromosomes. CROSSING OVER Occurs during Prophase I. Definition: Exchange of DNA between homologous chromosomes. Importance: Creates genetic variation. RANDOM ASSORTMENT Occurs during Metaphase I. Definition: Homologous pairs line up randomly. Importance: Creates unique chromosome combinations. MEIOSIS II Separates sister chromatids. MITOSIS VS MEIOSIS Mitosis * 2 cells produced * Diploid * Genetically identical * Growth and repair Meiosis * 4 cells produced * Haploid * Genetically different * Produces gametes NONDISJUNCTION Failure of chromosomes to separate properly during meiosis. Can result in extra or missing chromosomes. DOWN SYNDROME Cause: Extra chromosome 21. Chromosome Number: 47 Usually caused by nondisjunction during meiosis. DNA DNA = Deoxyribonucleic Acid Shape: Double Helix Function: Stores genetic information. NUCLEOTIDE Three Components: * Phosphate Group * Deoxyribose Sugar * Nitrogenous Base NITROGENOUS BASES Adenine (A) Thymine (T) Cytosine (C) Guanine (G) COMPLEMENTARY BASE PAIRING A pairs with T C pairs with G DNA REPLICATION Purpose: Make identical copies of DNA. Location: Nucleus Result: Two identical DNA molecules. TRANSCRIPTION Purpose: Create mRNA from DNA. Location: Nucleus DNA → mRNA Remember: RNA uses Uracil (U) instead of Thymine (T). TRANSLATION Purpose: Make proteins. Location: Ribosome mRNA is read and amino acids are joined together to form a protein. MUTATIONS A mutation is a change in DNA sequence. Types: * Deletion * Duplication * Inversion * Translocation DELETION DNA segment removed. DUPLICATION DNA segment repeated. INVERSION DNA segment reversed. TRANSLOCATION DNA segment moves to another chromosome. SEX-LINKED TRAITS Traits located on sex chromosomes. Most are located on the X chromosome. RED-GREEN COLOUR BLINDNESS Inheritance: X-linked recessive. XC = Normal Vision Xc = Colour Blind Male: XcY Colour blind boys inherit the allele from their mother because fathers pass a Y chromosome to their sons. TAY-SACHS DISEASE Cause: Missing enzyme that breaks down lipids in nerve cells. Inheritance: Autosomal recessive. Treatment: No cure currently available. SICKLE CELL ANEMIA Cause: Mutation in hemoglobin gene. Effects: * Sickle-shaped red blood cells * Reduced oxygen transport * Blocked blood vessels Inheritance: Autosomal recessive. HUNTINGTON’S DISEASE Cause: Dominant mutation. Effects: * Nervous system degeneration * Loss of motor control * Cognitive decline Inheritance: Autosomal dominant. KARYOTYPE A photograph of chromosomes arranged in pairs. Used to: * Determine sex * Detect chromosome abnormalities * Diagnose genetic disorders PEDIGREE A family tree used to track inheritance patterns. Symbols: Square = Male Circle = Female Shaded = Has trait CLONING Producing genetically identical organisms. Uses: * Research * Agriculture * Medicine * Conservation GENETIC COUNSELLING Provides information about: * Inherited disorders * Family risk * Testing options AMNIOCENTESIS Prenatal test in which amniotic fluid is sampled and fetal cells are analyzed. Can detect: * Genetic disorders * Chromosomal disorders GMOs Genetically Modified Organisms. Definition: Organisms whose DNA has been altered through biotechnology. Advantages: * Increased crop yield * Disease resistance * Pest resistance Disadvantages: * Ethical concerns * Environmental concerns DNA REPLICATION → TRANSCRIPTION → TRANSLATION DNA (Nucleus) ↓ Replication DNA Copy DNA ↓ Transcription mRNA mRNA ↓ Translation Protein Final Product: Protein RESPIRATORY SYSTEM Function: * Brings oxygen into the body * Removes carbon dioxide * Works with the circulatory system to supply cells with oxygen Why do organisms require oxygen and produce carbon dioxide? Oxygen is required for cellular respiration. Cellular Respiration: Glucose + Oxygen → Energy (ATP) + Carbon Dioxide + Water Cells use oxygen to release energy from food. Carbon dioxide is produced as a waste product and must be removed. ⸻ PATHWAY OF AIR Nasal Cavity ↓ Pharynx ↓ Larynx ↓ Trachea ↓ Bronchi ↓ Bronchioles ↓ Alveoli ⸻ NASAL CAVITY Functions: * Warms air * Moistens air * Filters air Nasal Hairs: * Trap large particles Mucus: * Traps dust and microorganisms Blood Capillaries: * Warm incoming air ⸻ PHARYNX Common passageway for: * Air * Food Also called the throat. ⸻ UVULA Functions: * Prevents food from entering nasal cavity * Helps with speech ⸻ EPIGLOTTIS Functions: * Covers trachea during swallowing * Prevents choking ⸻ LARYNX Also called the voice box. Contains vocal cords. ⸻ TRACHEA Also called the windpipe. Contains cartilage rings that prevent collapse. Lined with: * Cilia * Mucus ⸻ CILIA Tiny hair-like structures. Function: * Sweep mucus upward toward throat ⸻ BRONCHI Two branches of the trachea leading to lungs. Right Bronchus → Right Lung Left Bronchus → Left Lung ⸻ BRONCHIOLES Smaller branches inside lungs. Lead to alveoli. ⸻ ALVEOLI Tiny air sacs. Site of gas exchange. Adaptations: * Thin walls * Moist surface * Large surface area * Rich blood supply Gas Exchange: Oxygen moves: Alveoli → Blood Carbon Dioxide moves: Blood → Alveoli By diffusion. ⸻ BREATHING MECHANICS Two main muscles: 1. Diaphragm 2. Intercostal Muscles ⸻ INHALATION (INSPIRATION) Diaphragm: * Contracts * Moves downward Intercostal Muscles: * Contract * Lift ribs upward Result: * Chest cavity volume increases * Pressure decreases * Air enters lungs ⸻ EXHALATION (EXPIRATION) Diaphragm: * Relaxes * Moves upward Intercostal Muscles: * Relax Result: * Chest cavity volume decreases * Pressure increases * Air leaves lungs ⸻ MEDULLA OBLONGATA Located in the brainstem. Function: * Controls breathing rate Responds to: * Carbon dioxide levels More CO₂: * Faster breathing Less CO₂: * Slower breathing ⸻ LUNG VOLUMES Tidal Volume * Normal amount of air breathed in and out Inspiratory Reserve Volume * Extra air inhaled after normal breath Expiratory Reserve Volume * Extra air exhaled after normal breath Residual Volume * Air remaining in lungs after maximum exhalation Vital Capacity * Maximum amount of air exhaled after deepest breath Total Lung Capacity * Total amount of air lungs can hold ⸻ CIRCULATORY SYSTEM Functions: * Transport oxygen * Transport nutrients * Remove wastes * Maintain homeostasis * Transport hormones Humans have a CLOSED circulatory system. Blood remains inside vessels. ⸻ BLOOD VESSELS ARTERIES Function: * Carry blood away from heart Characteristics: * Thick walls * High pressure * Small lumen * No valves Usually oxygen-rich Exception: Pulmonary artery ⸻ VEINS Function: * Carry blood toward heart Characteristics: * Thin walls * Low pressure * Large lumen * Valves present Usually oxygen-poor Exception: Pulmonary vein ⸻ CAPILLARIES Smallest blood vessels. Functions: * Gas exchange * Nutrient exchange * Waste exchange Walls are one cell thick. ⸻ HEART STRUCTURE Blood Flow: Body ↓ Vena Cava ↓ Right Atrium ↓ Right Ventricle ↓ Pulmonary Artery ↓ Lungs ↓ Pulmonary Vein ↓ Left Atrium ↓ Left Ventricle ↓ Aorta ↓ Body ⸻ HEART CHAMBERS Right Atrium * Receives deoxygenated blood Right Ventricle * Pumps blood to lungs Left Atrium * Receives oxygenated blood Left Ventricle * Pumps blood to body ⸻ SEPTUM Wall separating left and right sides of heart. Prevents mixing of blood. ⸻ HEART VALVES Function: * Prevent backflow of blood Types: Atrioventricular (AV) Valves Pulmonary Semilunar Valve Aortic Semilunar Valve ⸻ SA NODE Sinoatrial Node Known as: * Natural pacemaker Initiates heartbeat. ⸻ AV NODE Atrioventricular Node Receives signal from SA node. Delays impulse slightly. Allows ventricles to fill before contraction. ⸻ BLOOD Components: 1. Plasma 2. Red Blood Cells 3. White Blood Cells 4. Platelets ⸻ PLASMA Liquid component of blood. Functions: * Transport nutrients * Transport hormones * Transport wastes ⸻ RED BLOOD CELLS (ERYTHROCYTES) Function: * Carry oxygen Contain: * Hemoglobin ⸻ HEMOGLOBIN Protein in red blood cells. Function: * Binds oxygen Allows oxygen transport. ⸻ WHITE BLOOD CELLS (LEUKOCYTES) Function: * Fight infection * Defend body Part of immune system. ⸻ PLATELETS Function: * Blood clotting Prevent blood loss. ⸻ BLOOD PRESSURE Force of blood against artery walls. Measured using: Sphygmomanometer Example: 120/80 120 = Systolic Pressure 80 = Diastolic Pressure ⸻ SYSTOLIC PRESSURE Pressure when heart contracts. ⸻ DIASTOLIC PRESSURE Pressure when heart relaxes. ⸻ HYPERTENSION High blood pressure. Can increase risk of: * Stroke * Heart attack * Kidney disease ⸻ STROKE VOLUME Amount of blood pumped per heartbeat. ⸻ CARDIAC OUTPUT Amount of blood pumped per minute. Formula: Cardiac Output = Heart Rate × Stroke Volume ⸻ ECG Electrocardiogram Measures electrical activity of heart. Used to detect: * Irregular heartbeat * Heart damage ⸻ PULMONARY CIRCULATION Heart → Lungs → Heart Purpose: * Oxygenate blood ⸻ SYSTEMIC CIRCULATION Heart → Body → Heart Purpose: * Deliver oxygen to tissues ⸻ HOMEOSTASIS DURING EXERCISE Body responds by: * Increasing heart rate * Increasing breathing rate * Increasing cardiac output * Redirecting blood to muscles * Sweating to cool body Purpose: Maintain stable internal conditions. ⸻ DIGESTIVE SYSTEM Functions: * Break down food * Absorb nutrients * Eliminate waste ⸻ DIGESTIVE TRACT Mouth ↓ Pharynx ↓ Esophagus ↓ Stomach ↓ Small Intestine ↓ Large Intestine ↓ Rectum ↓ Anus ⸻ MECHANICAL DIGESTION Physical breakdown of food. Examples: * Chewing * Churning ⸻ CHEMICAL DIGESTION Chemical breakdown of food using enzymes. Examples: * Amylase * Pepsin ⸻ SALIVA Functions: 1. Moistens food 2. Contains amylase Amylase begins carbohydrate digestion. ⸻ TONGUE Functions: 1. Forms bolus 2. Pushes food for swallowing ⸻ ESOPHAGUS Moves food to stomach. Uses: Peristalsis ⸻ PERISTALSIS Wave-like muscular contractions. Move food through digestive tract. ⸻ STOMACH Functions: * Stores food * Mixes food * Begins protein digestion Produces: * HCl * Pepsin * Mucus ⸻ HCl Hydrochloric Acid Functions: * Kills bacteria * Activates pepsin ⸻ PEPSIN Function: * Digests proteins ⸻ MUCUS Function: * Protects stomach lining ⸻ CHYME Semi-liquid food mixture leaving stomach. ⸻ HEARTBURN Cause: Stomach acid enters esophagus. Usually caused by weakened cardiac sphincter. ⸻ SMALL INTESTINE Main site of: * Digestion * Absorption Adaptations: * Long length * Folds * Villi * Microvilli Large surface area increases absorption. ⸻ DUODENUM First section. Functions: * Receives bile * Receives pancreatic enzymes * Most chemical digestion ⸻ JEJUNUM Main nutrient absorption. ⸻ ILEUM Final nutrient absorption. ⸻ VILLI Finger-like projections. Function: Increase surface area. ⸻ LIVER Functions: * Produces bile * Processes nutrients * Detoxifies blood ⸻ GALL BLADDER Functions: * Stores bile * Releases bile into small intestine ⸻ PANCREAS Functions: * Produces digestive enzymes * Produces bicarbonate ⸻ BILE Function: Emulsifies fats. Breaks large fat droplets into smaller droplets. Makes fat digestion easier. ⸻ DIGESTION OF CARBOHYDRATES Mouth: * Amylase begins digestion Small Intestine: * Pancreatic amylase continues digestion End Product: Glucose ⸻ DIGESTION OF PROTEINS Stomach: * Pepsin begins digestion Small Intestine: * Trypsin continues digestion End Product: Amino Acids ⸻ DIGESTION OF LIPIDS Small Intestine: * Bile emulsifies fats * Lipase digests fats End Product: Fatty Acids + Glycerol ⸻ EVOLUTION Evolution: Change in populations over time. Individuals do NOT evolve. Populations evolve. ⸻ DARWIN Proposed: Natural Selection Book: On the Origin of Species ⸻ WALLACE Independently developed theory of natural selection. ⸻ LAMARCK Proposed: Inheritance of acquired characteristics Example: Giraffes stretch necks and pass longer necks to offspring. This theory is incorrect. ⸻ NATURAL SELECTION Requirements: 1. Variation 2. Overproduction 3. Competition 4. Differential Survival 5. Reproduction Result: Adaptation ⸻ ADAPTATION Inherited characteristic that increases survival and reproduction. ⸻ SELECTIVE ADVANTAGE A characteristic that improves survival or reproduction. Example: Antibiotic resistance ⸻ SELECTIVE PRESSURE Environmental factor that influences survival. Examples: * Predators * Disease * Climate * Competition ⸻ VARIATION Differences among individuals in a population. Sources: * Mutation * Crossing Over * Random Assortment ⸻ MUTATION Ultimate source of new alleles. Creates genetic variation. ⸻ FOSSIL Preserved remains or traces of organisms. ⸻ FOSSIL RECORD Collection of fossils showing evolutionary history. Provides evidence for evolution. ⸻ RADIOACTIVE DATING Uses radioactive isotopes to determine fossil age. ⸻ UNIFORMITARIANISM Proposed by Lyell. Earth changes gradually over long periods of time. ⸻ CATASTROPHISM Proposed by Cuvier. Earth shaped by sudden catastrophic events. ⸻ BIOGEOGRAPHY Study of species distribution around Earth. Provides evidence for evolution. ⸻ EMBRYOLOGY Study of embryos. Similar embryos suggest common ancestry. ⸻ HOMOLOGOUS STRUCTURES Same evolutionary origin. Different functions. Example: Human arm Whale flipper Bat wing Evidence of common ancestry. ⸻ ANALOGOUS STRUCTURES Different origins. Same function. Example: Bird wing Insect wing Not evidence of close ancestry. ⸻ VESTIGIAL STRUCTURES Structures with little or no function. Examples: * Human appendix * Whale pelvis Evidence of evolution. ⸻ MIMICRY One species resembles another. Example: Syrphid fly resembles wasp. Provides protection. ⸻ ARTIFICIAL SELECTION Humans select traits. Examples: * Dog breeding * Crop breeding ⸻ DIRECTIONAL SELECTION One extreme phenotype favored. Graph shifts in one direction. ⸻ STABILIZING SELECTION Average phenotype favored. Extremes selected against. ⸻ DISRUPTIVE SELECTION Both extremes favored. Middle selected against. ⸻ GENETIC DRIFT Random change in allele frequencies. Most significant in small populations. ⸻ FOUNDER EFFECT Small group starts new population. Different allele frequencies from original population. ⸻ BOTTLENECK EFFECT Population drastically reduced. Loss of genetic variation. ⸻ GENE FLOW Movement of alleles between populations. Occurs through migration. ⸻ NON-RANDOM MATING Individuals choose specific mates. Can reduce variation. ⸻ SPECIES A group of organisms that can interbreed in nature and produce fertile offspring. ⸻ SPECIATION Formation of new species. ⸻ ALLOPATRIC SPECIATION Requires: Geographic isolation Example: Mountain separates populations. ⸻ SYMPATRIC SPECIATION Occurs without geographic isolation. ⸻ PRE-ZYGOTIC ISOLATION Prevents fertilization. Examples: * Different mating seasons * Different mating songs * Different habitats ⸻ POST-ZYGOTIC ISOLATION Occurs after fertilization. Example: Sterile hybrids Example: Mule DIVERSITY Prokaryotes vs Eukaryotes PROKARYOTES * No nucleus * No membrane-bound organelles * Circular DNA * Smaller * Examples: Eubacteria, Archaebacteria EUKARYOTES * Nucleus present * Membrane-bound organelles * Linear chromosomes * Larger * Examples: Protists, Fungi, Plants, Animals Three Differences: 1. Nucleus vs no nucleus 2. Organelles vs no organelles 3. Larger vs smaller ⸻ Taxonomy Kingdom Phylum Class Order Family Genus Species Mnemonic: King Philip Came Over For Good Soup ⸻ Binomial Nomenclature Genus + Species Example: Homo sapiens Rules: * Genus capitalized * Species lowercase * Italicized Purpose: * Universal naming system * Avoids confusion * Shows relationships ⸻ Dichotomous Key Used to identify organisms using paired choices. Example: 1a Has wings → Step 2 1b No wings → Step 3 ⸻ Six Kingdoms 1. Archaebacteria 2. Eubacteria 3. Protista 4. Fungi 5. Plantae 6. Animalia ⸻ VIRUSES Virus Structure: * DNA or RNA * Capsid * Attachment proteins * Sometimes envelope Why Viruses Are Not Living: * Not made of cells * Cannot reproduce independently * No metabolism * Need host cell ⸻ DNA Virus vs RNA Virus DNA Virus: * Contains DNA * More stable RNA Virus: * Contains RNA * Mutates faster ⸻ Lytic Cycle Attachment ↓ Penetration ↓ Replication ↓ Assembly ↓ Lysis Host cell bursts. ⸻ Lysogenic Cycle Attachment ↓ Penetration ↓ Integration into host DNA ↓ Host reproduces ↓ Virus DNA copied Cell survives initially. ⸻ ARCHAEBACTERIA Characteristics: * Prokaryotic * Unicellular * Extreme environments Three Groups: Methanogens * Produce methane Halophiles * Salt-loving Thermoacidophiles * Hot acidic environments ⸻ EUBACTERIA Characteristics: * Prokaryotic * Peptidoglycan cell wall * Binary fission Examples: * E. coli * Streptococcus ⸻ Binary Fission DNA Replication ↓ Cell Growth ↓ Cell Division ↓ Two Identical Cells ⸻ Conjugation DNA transfer through pilus. Importance: * Genetic variation * Antibiotic resistance ⸻ Antibiotic Resistance Mutation ↓ Antibiotic kills susceptible bacteria ↓ Resistant bacteria survive ↓ Resistant bacteria reproduce Natural Selection ⸻ PROTISTS Characteristics: * Eukaryotic * Mostly unicellular * Aquatic Three Groups: Animal-like * Amoeba * Paramecium Plant-like * Algae * Euglena Fungus-like * Slime molds ⸻ Amoeba * Uses pseudopods * Phagocytosis ⸻ Algae * Photosynthetic * Oxygen producer ⸻ Euglena * Chloroplasts * Flagellum * Photosynthesis * Can also feed heterotrophically ⸻ Malaria Cause: Plasmodium Kingdom: Protista ⸻ FUNGI Characteristics: * Eukaryotic * Heterotrophic * Chitin cell walls * Reproduce with spores Examples: * Mushrooms * Mold * Yeast ⸻ External Digestion Release enzymes ↓ Digest food outside body ↓ Absorb nutrients ⸻ Fungi vs Plants FUNGI * Heterotrophic * Chitin * No chloroplasts PLANTS * Autotrophic * Cellulose * Chloroplasts ⸻ PLANTS Biodiversity vs Monoculture BIODIVERSITY * Many species * Stable ecosystem * Disease resistance MONOCULTURE * One crop species * Low diversity * Disease risk ⸻ Bryophytes Definition: Nonvascular plants Examples: * Mosses * Liverworts Characteristics: * No xylem * No phloem * Need water for reproduction ⸻ Vascular Plants Contain: * Xylem * Phloem ⸻ Xylem Function: Water and minerals Direction: Roots → Leaves ⸻ Phloem Function: Sugars Direction: Throughout plant ⸻ Alternation of Generations Sporophyte (2n) ↓ meiosis Spores (n) ↓ Gametophyte (n) ↓ Gametes ↓ fertilization Zygote (2n) ↓ Sporophyte ⸻ Moss Life Cycle Spores ↓ Gametophyte ↓ Egg + Sperm ↓ Zygote ↓ Sporophyte ↓ Capsule ↓ Spores Know: * Capsule * Sporophyte * Gametophyte * Spores ⸻ Fern Life Cycle Fern ↓ Sori ↓ Spores ↓ Prothallus ↓ Gametes ↓ Fertilization ↓ Young Fern Know: * Frond * Sori * Sporangia * Prothallus ⸻ Gymnosperms Characteristics: * Naked seeds * Cones * Wind pollination * Evergreen Examples: * Pine * Spruce * Fir ⸻ Angiosperms Characteristics: * Flowers * Fruit * Seeds enclosed Examples: * Apple tree * Rose * Maple ⸻ Flower Structure Anther * Produces pollen Pollen Grain * Male gamete Stigma * Receives pollen Style * Connects stigma and ovary Ovary * Contains ovules Ovule * Female gamete Petals * Attract pollinators ⸻ Plant Tissues Meristematic * Growth Dermal * Protection Ground * Photosynthesis * Storage Vascular * Transport ⸻ Leaf Structure Blade * Main leaf surface Petiole * Connects leaf to stem Cuticle * Reduces water loss Palisade Mesophyll * Photosynthesis Spongy Mesophyll * Gas exchange Veins * Xylem + Phloem ⸻ Stomata Openings in leaves. Functions: * Gas exchange * Water loss ⸻ Guard Cells Control opening and closing of stomata. ⸻ Transpiration Water loss from leaves. Functions: * Pulls water upward * Cools plant * Moves minerals ⸻ Simple vs Compound Leaves Simple: * One blade Compound: * Multiple leaflets ⸻ Monocots vs Dicots MONOCOTS * 1 cotyledon * Parallel veins * Fibrous roots * Flower parts in 3s Examples: Corn Grass DICOTS * 2 cotyledons * Net veins * Taproot * Flower parts in 4s or 5s Examples: Bean Maple ⸻ Seeds Contain: * Embryo * Stored food * Seed coat Functions: * Protection * Survival * Dispersal ⸻ Seed Dispersal Wind * Dandelion Water * Coconut Animals * Burrs Explosive * Touch-me-not ⸻ Fruit vs Vegetable Fruit: * Comes from ovary * Contains seeds Examples: Tomato Apple Pepper Vegetable: * Root, stem, leaf, or flower Examples: Carrot Celery Broccoli ⸻ Factors Affecting Plant Growth 1. Light 2. Water 3. Carbon dioxide 4. Temperature 5. Soil nutrients 6. Oxygen 7. Soil pH 8. Space 9. Pollinators 10. Disease and pests

MMiPeople Francesco Redi: scientist who tested spontaneous generation with rotting meat and maggot formation with an open container, sealed container, and gauze-covered container, and refuted spontaneous generation Needham: scientist who tested spontaneous generation with boiling chicken broth, sealing the container, and waiting a few days to assess for microbial growth, and supported spontaneous generation Spallanzani: scientist who tested spontaneous generation with further testing, Needham’s experiment, and tested with an open and closed container that was later opened, and refuted spontaneous generation Louis Pasteur: scientist who used swan-neck flasks in his experiment and definitively refuted spontaneous generation Anthony van Leeuwenhoek: scientist who was the first to observe eukaryotic microbes, calling them “wee animalcule” Robert Hooke: coined the term “cell” when looking at cork Matthias Schleiden: observed cells in plant tissue Theodor Schwann: observed cells in animal tissue Rudolf Virchow and Robert Remark: observed cells dividing to make new cells (not mitosis) Hippocrates: suggested disease has natural causes Thucydides: advocated for evidence-based analysis of cause and effect and suggested immunity after observing plague survivors didn't get sick again Marcus Terentius Varro: the first to propose that things we cannot see cause disease Ignaz Semmelweis: physician who observed the spread of disease among patients in different sides of the hospital and instituted hand washing between patients to reduce the spread of disease from patient to patient via healthcare workers Joseph Lister: surgeon who observed post-surgical infection and instituted hand washing and sterilization of medical equipment with 5% phenol solution for less disease Robert Koch: scientist who developed Koch’s postulates to determine the cause of disease and had a rivalry with Louis Pasteur John Snow: questioned the London cholera outbreak and asked questions to the people who had been infected about where they had been and what they had eaten or drank, and noticed that everyone who had cholera used one of two water pumps Classification of microbes What are the 2 domains that are composed of all microbes? Bacteria and Archaea What domain of life is composed only of some microbes? Eukarya What types of microbes do not fit into the domains of life? Viruses and Prions Prions: unicellular organisms in the domains Bacteria and Archaea with no nucleus and have cell walls Viruses: acellular and domainless (not alive) Eukaryotes: unicellular OR multicellular organisms, in domain Eukarya, have a nucleus, have membrane-bound organelles, and include fungi, algae, protazoa, and helminths How many times bigger are bacteria than viruses? 100x A cell is around how many times bigger than an individual bacteria? 10x Cell structures Know the function, general location, and whether they are shared with eukaryotes (if yes similarities/differences) of the following structures: 1. Nucleoid: contains chromosome(s) and nuclear-associated proteins that are usually haploid and circular near the center of the cell, which hold the DNA genetic information without a membrane Eukaryotes = have a nucleus, are diploid and linear Prokaryotes = have nucleoid, are haploid and circular 2. Ribosomes: work with mRNA protein synthesis, made up of proteins and RNA, found in cytoplasm Eukaryotes: 80S, 60 large, 40 small (18S sequencing) Prokaryotes: 70S, 50 large, 30 small (16S sequencing) 3. Cytoplasm: fluid inner layer 4. Fimbriae: short, bristle-like projections for attachment to surfaces 5. Endospores: not all bacteria have, protect bacteria in a dormant state/ harsh environment, found inside bacteria, sporulation = the process of becoming dormant, germination = process of becoming active 6. Plasma membrane: semipermeable, composed of lipids and proteins, controls transport into and out of cell, most inner layer before cytoplasm (ex: facilitated diffusion, active transport, diffusion, endocytosis (Eukaryotes), sterols (Eukaryotes), and cholesterol (Eukaryotes) Same for Eukaryotes 7. Cell wall: protects against harsh changing environments and osmotic stress, contains peptidoglycan in bacteria, contains Gram + and Gram - Steps of Gram stain: dye with crystal violet, iodine (mordant), alcohol (decolorizer), and safranin red If mycobacteria complete an acid-fast stain Gram + has LTA an TA and one membrane Gram - has LPS and 2 membranes 8. Capsule: protective protein shell, outermost layer 9. Pilus: medium projection, adheres to surfaces, does DNA gene transfer 10. Flagellum: long protein projections made of flagellin for movement (ex: 1= monotrichous, one at each end = amphitrichous, many at one end = lophotrichous, many flagella all over the cell = peritrichous 11. Plasmid: circular, double-stranded DNA not part of the chromosome, and can have 1-100 of the same or different plasmids to help with gene transfer, antibiotic resistance, and virulence factors, found anywhere in the cytoplasm Not part of Eukaryotes 12. Inclusion: not all bacteria have, helps with the storage of nutrients and other materials, has protein shell, and is found in cytoplasm (ex: lipid droplets store fats, volutin stores inorganic phosphates, sulfur inclusions store sulfur, gas bubbles store gas for buoyancy in water, magnetosomes store metals for movement) Not part of Eukaryotes; instead, they have vesicles for storage All cellular microbes have what four (4) components? Cell Membrane, Cytoplasm, Ribosomes, and DNA What is the only component of all cells that viruses have? Cytoplasm Know/ be able to identify the shapes of bacteria Round shape: coccus Rod shape: bacillus Vibrio: curved rod shape Short rods with combo of coccus and bacillus: coccobacillus Wavy spiral shape: Spirillum Coiled spiral shape: Spirochete Microbial growth Phases of growth Lag Phase: bacteria gear up for replication by increasing cell size, metabolism, and protein synthesis Log Phase: exponential growth phase, where bacteria actively replicate and are most susceptible to antibiotics Stationary Phase: growth curve flatlines bc bacteria are dying at same rate of growth, begin survival mode and sporulation, produce secondary metabolites, and produce virulence factors, and are low on space, nutrients, and oxygen Death Phase: bacteria die at exponential rate, increase amount of toxic waste, release spores, some spontaneously lyse to feed others, and persister cells refuse to die How do microbes replicate? Through binary fission, fragmentation, budding, and sexually What is a biofilm? Communities of bacteria (steps: colonization, attachment, replication, make EPS with antibiotic resistance, EPS kick bacteria out to replicate somewhere else) How does quorum sensing work? Bacteria want to work together, so they secrete autoinducers, and when you activate enough receptors, they activate a response Growth requirements – classifications and adaptations 1. Oxygen requirements Obligate Aerobes: need O2 to survive Obligate Anaerobes: die in presence of O2 Faculative: mostly need O2 but can survive without it Microaerophiles: need O2 for survival but not atmospheric O2 (low levels) Aerotolerant: can survive with or without oxygen Capnophiles: like high CO2 and low O2 2. pH requirements Acidophiles: low pH (2-4), high H+ environments, efflux pumps to remove H+ ions, changes membrane composition to withstand low pH Neutrophiles: neutral pH (7), found within body Alkaliphiles: basic pH (9-10), modified lipid protein structures, modified electron transport system that use Na+ instead of H+, high OH- environment 3. temperature requirements Psychrophiles: like freezing temperatures a below 0-15 degrees, die at or above 20 degrees, found in cold lakes or the ocean floor, have hydrophobic proteins to increase flexibility, have decreased secondary stabilizing bonds Psychrotolerant: cold not ideal but wont kill them, live between 4-25 degrees (fridge temperature) Mesophiles: moderate temperatures, 20-40 degrees, grow in body Thermophiles: hot environments 50-80 degrees, hot springs, geothermal soil Hyperthermophiles: very hot environments 80-110 degrees, found in hydrothermal vents, increased saturation in membranes, increased stabilizing bonds, alter amino acids to prevent denaturation 4. osmolarity requirements Hypertonic: more water out Hypotonic: more water in Isotonic: equal water in and out Halotolerant: dont require salt but can grow in high salt environments Halophiles: love salt, found in ocean and salt lakes, have increased cytoplasmic glycerol, have efflux pumps for salt 5. barometric requirements Barophile: survive high atmospheric environments like the bottom of the ocean (something at top of mountain has low atmospheric pressure) Microbial Metabolism Means of generating energy (do the processes require oxygen?, which gives the most energy?) Glycolysis: does not require O2 bc it can be used during fermentation, used 2 ATP, makes 4 ATP, NET 2 ATP Kreb’s cycle: requires O2; NET after 1 round= 1ATP, 1 NADH, 1FADH2 (x2 for second round) Electron transport: requires O2, biggest payout of ATP with NET 34 ATP Photosynthesis: does not require O2 as it is a waste product, can do oxygenic and anoxygenic Microbial genetics DNA Replication – enzymes and functions DNA gyrase: unwinds DNA (enzyme) Helicase: unzips DNA (enzyme) Single-stranded binding proteins: bind to DNA so doesnt close back up (protein) Single-stranded binding proteins: bind to DNA so doesnt close back up (protein) DNA polymerase III: lay down new DNA nucleotides, synthesizes leading and lagging strands 5’ →3’(enzyme) DNA polymerase I: removes RNA primers (enzyme) DNA Ligase: seals RNA primers (enzyme) Topoisomerase 4: separates 2 circular chromosomes Transcription and translation – enzymes and function 1. RNA polymerase: turns DNA→ mRNA (transcription) 2. Ribosomes: 30S small, 50S large, 70S total 3. tRNA: A,P, and E sites, bacteria links transcription and translation bc no nucleus, has anticodon at opposite long 3’ end, high energy bond, same active translation process as Eukaryotes Be able to do DNA base pairing, transcription, and translation (given codon table) Also know differences between prokaryotic and eukaryotic Replication, transcription, and translation Genetic Diversity – how does this work? 1. Transformation: uptake of plasmid into different bacteria and is incorporated into its genetic material 2. Transduction: bacteriophage inserts its plasmid into a bacteria (virus that infects a bacteria) 3. Conjugation: like plasmid transfer (ex: rolling circle replication), “bacterial sex” 4

Objectives come from your Unit 3 sheet  and the content/examples come from the PowerPoints . ⸻ UNIT 3 COMPLETE STUDY GUIDE (Based strictly on your slides + objectives) ⸻ CHAPTER 11 — CONTROLLING MICROBIAL GROWTH Difference Between Antisepsis, Disinfection, Sanitization, Sterilization, Degerming, Decontamination Sterilization Complete destruction of all microbial life including viruses and endospores. Examples from slides: • Surgical instruments • Syringes • Packaged foods Endospores must be destroyed for something to be considered sterile.  ⸻ Disinfection Destroys most vegetative pathogens on nonliving surfaces. Examples: • Disinfecting medical equipment • Hospital surfaces ⸻ Antisepsis Use of antimicrobial chemicals on living tissue. Examples: • Skin prep before surgery • Cleaning wounds ⸻ Degerming Mechanical removal of microbes by scrubbing. Example: • Handwashing ⸻ Sanitization Reduces microbial numbers to public health safe levels. Examples: • Cleaning food preparation surfaces • Restaurant sanitation ⸻ Decontamination General removal of microbes from objects or surfaces. Example: • Cleaning contaminated hospital equipment ⸻ Difference Between Static and Cidal Cidal Kills microbes. Example Bactericidal antibiotics. ⸻ Static Stops growth but does not kill. Example Bacteriostatic antibiotics. ⸻ Variables That Influence Effectiveness of Antimicrobial Methods 1. Population size Large populations require more time to kill. 2. Nature of microbes Some microbes are more resistant. Example: Bacterial endospores. 3. Temperature Higher temperature increases killing. 4. Concentration of agent 5. Contact time 6. Organic matter present Example: Blood or mucus interfering with disinfectants. 7. Mode of action of agent 8. Biofilms Biofilms protect microbes from antimicrobials.  ⸻ Most Resistant vs Least Resistant Microbes Most resistant: Bacterial endospores Reason: Thick protective layers. ⸻ Less resistant: • Mycobacteria • Gram-negative bacteria • Gram-positive bacteria • Fungi • Viruses Endospores are the target of sterilization methods.  ⸻ Mechanisms of Antimicrobial Agents Agents work by damaging: Cell wall Example Detergents and alcohol disrupt cell wall. ⸻ Cell membrane Effects • Loss of permeability • Leakage of molecules ⸻ Proteins Agents denature proteins. Examples • Heat • Alcohol • Strong acids ⸻ DNA and RNA Example Radiation damaging DNA. ⸻ Practical Concerns When Choosing Control Method Consider: • Does item require sterilization or disinfection? • Can item tolerate heat, pressure, radiation, chemicals? • Cost effectiveness • Safety • Ability of agent to penetrate surfaces.  ⸻ PHYSICAL AND MECHANICAL METHODS ⸻ Pasteurization vs Sterilization Pasteurization: Reduces microbial numbers but does not sterilize. Used for: Milk and beverages. Sterilization: Destroys all microbes including endospores. ⸻ Boiling Kills many pathogens but may not destroy endospores. ⸻ Autoclaving Uses steam under pressure. Conditions from slides: 121°C 15 minutes 15 psi Mechanism: Denatures proteins and disrupts metabolism.  ⸻ Most Rigorous Heat Method Incineration (dry heat) Burns microbes completely. ⸻ Ionizing Radiation vs UV Radiation Ionizing radiation Examples: Gamma rays X-rays Effect: Destroys DNA and proteins. Highly penetrating. ⸻ UV radiation Example: Germicidal lamps. Mechanism: Forms pyrimidine dimers (thymine dimers). Effect: DNA replication blocked.  ⸻ Filtration Removes microbes from liquids or air. Examples: • Water purification • Milk filtration • Air filtration systems • HEPA filters • N95 masks HEPA filters remove 99.97% of particles.  ⸻ Osmotic Pressure High salt or sugar removes water from microbes. Examples: Salt: Cured meats Sugar: Jams and jellies Causes plasmolysis and prevents growth.  ⸻ Cold and Drying Cold: Slows microbial metabolism but rarely kills microbes. Drying (desiccation): Removes water necessary for microbial metabolism. Example: Freeze drying (lyophilization).  ⸻ CHEMICAL METHODS ⸻ Characteristics of Good Chemical Antimicrobials • Rapid action • Effective at low concentrations • Broad spectrum • Stable • Non-toxic to tissues • Affordable • Effective in presence of organic matter  ⸻ Major Chemical Agents ⸻ Halogens Examples: • Chlorine • Iodine Common example: Household bleach (sodium hypochlorite) Mechanism: Oxidizes cellular molecules and damages enzymes.  ⸻ Phenols Mechanism: Disrupt cell membranes and denature proteins. Examples: Phenolic disinfectants. ⸻ Alcohols Examples: • Ethanol • Isopropanol Mechanism: Denature proteins and disrupt membranes. Common use: Hand sanitizers. ⸻ Quats Quaternary ammonium compounds. Mechanism: Disrupt membranes. Example: Lysol wipes ⸻ Peroxides Example: Hydrogen peroxide. Mechanism: Forms reactive oxygen molecules that damage cells. ⸻ Detergents / Surfactants Mechanism: Break down lipid membranes. Examples: Soap and cleaning detergents.  ⸻ CHAPTER 12 — ANTIBIOTICS ⸻ Alexander Fleming Discovered penicillin in 1928 from the fungus Penicillium.  ⸻ Characteristics of a Good Antimicrobial Drug • Selective toxicity • High therapeutic index • Targets unique microbial structures • Effective against pathogen • Minimal harm to microbiota  ⸻ Selective Toxicity Ability of a drug to kill microbes without harming host cells. Example: Penicillin targets bacterial cell walls, which human cells lack. ⸻ Susceptibility Tests ⸻ Kirby-Bauer Disc diffusion test. Antibiotic discs placed on bacterial culture. Zone of inhibition measured. Results: Sensitive Resistant  ⸻ MIC Minimum inhibitory concentration. Smallest drug concentration preventing visible growth. ⸻ MBC Minimum bactericidal concentration. Smallest concentration that kills bacteria. ⸻ Therapeutic Index TI = toxic dose / therapeutic dose Example from slides: TI of 10 safer than TI of 1.1.  ⸻ Antibiotic Mechanisms ⸻ Cell Wall Inhibitors Example: Penicillin Mechanism: Prevents cross-linking of NAM-NAG peptidoglycan. Cell bursts due to osmotic pressure. Other examples: • Methicillin • Cephalosporins  ⸻ Cell Membrane Disruption Examples: • Polymyxin • Daptomycin • Colistin Mechanism: Creates pores causing leakage.  ⸻ Protein Synthesis Inhibitors Example: Tetracycline Mechanism: Blocks 30S ribosomal subunit. Other examples: • Erythromycin • Azithromycin • Chloramphenicol  ⸻ DNA / RNA Inhibitors Example: Fluoroquinolones Examples: • Ciprofloxacin • Levofloxacin Mechanism: Inhibit DNA gyrase. ⸻ Metabolic Pathway Inhibitors Example: Sulfa drugs Block folic acid synthesis. Example drug: Bactrim.  ⸻ Drugs for Eukaryotic Pathogens ⸻ Antifungals Examples: • Fluconazole • Amphotericin B • Azoles Target ergosterol in fungal membranes. ⸻ Antiprotozoal Drugs Examples: • Metronidazole • Chloroquine ⸻ Antihelminthic Drugs Examples: • Pyrantel • Mebendazole • Ivermectin  ⸻ Antiviral Drugs Targets: • Viral attachment • Viral transcription/translation • Viral assembly or release Examples: Acyclovir Blocks viral DNA replication. Tamiflu Prevents influenza virus release.  ⸻ HIV Drugs Target steps in HIV replication: 1 Reverse transcriptase 2 Integrase 3 Protease 4 Viral attachment Combination therapy prevents resistance. ⸻ Antibiotic Resistance ⸻ How Resistance Develops • Mutation • Natural selection • Overuse of antibiotics ⸻ Mechanisms of Resistance • Drug-destroying enzymes • Efflux pumps • Target modification • Reduced permeability  ⸻ CHAPTER 13 — MICROBIOTA ⸻ Normal Microbiota Microorganisms living on body surfaces without causing disease. Examples from slides: Skin: Staphylococcus epidermidis Gut: Escherichia coli Breast milk microbes: • Bifidobacterium • Lactobacillus • Streptococcus • Clostridium  ⸻ Benefits of Microbiota • Produce vitamins • Digest food • Stimulate immune system • Produce neurotransmitters • Prevent pathogen colonization  ⸻ Dysbiosis Imbalance in microbiota. Associated diseases: • Diabetes • Obesity • Cancer • Asthma • Allergies • Heart disease  ⸻ Microbiota Development Microbiota develop: 1 During birth 2 Through breast milk 3 Environmental exposure Stable microbiome forms by age 3. ⸻ Probiotics vs Prebiotics Probiotics: Live microbes that improve microbiota. Example: Yogurt. ⸻ Prebiotics: Food that feeds beneficial microbes. Examples: • Garlic • Onions • Asparagus • Agave • Artichokes  ⸻ Fecal Microbiota Transplant Transfer of microbiota from healthy donor. Used for: Clostridioides difficile infections Success rate: 70–90%.  ⸻ Virulence Factors Examples: Adhesion structures: Capsules, fimbriae Exoenzymes: Hyaluronidase Coagulase Biofilms increase resistance.  ⸻ Toxins ⸻ Exotoxins Secreted protein toxins. Examples: • Cytotoxins • Neurotoxins • Enterotoxins ⸻ Endotoxins Found in gram-negative bacteria. Example: LPS containing lipid A. Effects: • Fever • Inflammation • Shock  ⸻ CHAPTER 14 — EPIDEMIOLOGY ⸻ Epidemiology Study of disease frequency, distribution, and control in populations.  ⸻ Epidemiological Terms Index case: First identified patient. Incidence: Number of new cases. Prevalence: Total existing cases. Mortality rate: Deaths in a population. Case fatality rate: Deaths among infected individuals.  ⸻ Disease Occurrence Sporadic: Random cases. Endemic: Constant presence. Outbreak: Localized increase. Epidemic: Large regional increase. Pandemic: Worldwide epidemic.  ⸻ Healthcare-Associated Infections (HAIs) Common examples: • CAUTI Catheter-associated urinary tract infection • CLABSI Central line bloodstream infection • Surgical site infections • Ventilator associated infections  ⸻ Causes of HAIs • Low patient immunity • Antibiotic resistant organisms • Invasive procedures • Healthcare worker transmission Example: Healthcare workers moving between patients.  ⸻ Prevention of HAIs • Medical asepsis • Surgical asepsis • Universal precautions • Infection control officers Examples: • Needlestick precautions • Surface decontamination • Barrier protection  ⸻ If you want, I can also give you the 20–30 questions your professor is MOST likely to put on the exam from these slides. Micro professors tend to repeat the same exact conceptual questions every semester, and your slides have some really obvious ones.

peptidoglycan, antibiotics, and resistance

BIOL 3150 – Microbiology for the Healthcare Professions Midterm Study Guide Explanation 1. Contamination Purpose of Disinfecting Surfaces Disinfecting surfaces is important to: Kill or reduce microorganisms on surfaces Prevent cross-contamination between patients, samples, and healthcare workers Reduce spread of infectious disease Maintain a sterile working environment Common disinfectants include alcohol, bleach, and hospital-grade disinfectants. Why Hand Washing is Important Hand washing: Removes transient microorganisms Prevents transmission of pathogens Protects both healthcare workers and patients Reduces healthcare-associated infections (HAIs) Proper handwashing typically includes: Wet hands Apply soap Scrub at least 20 seconds Rinse Dry with clean towel 2. Specimen Collection Sterile Containers vs Nonsterile Containers Sterile containers Free from microorganisms Used when contamination must be prevented Examples: Blood cultures Urine cultures Wound cultures Nonsterile containers Used when normal microbes are already present Examples: Stool samples Sputum samples (sometimes) Information Needed When Labeling a Specimen Proper labeling prevents errors. Required information usually includes: Patient name Patient ID number Date and time of collection Type/source of specimen Collector’s initials Physician or test ordered Transport Media Transport media keeps microorganisms alive during transport to the laboratory. Purpose: Prevents organisms from drying out Prevents overgrowth of contaminants Maintains viability of pathogens Example: swabs placed in transport tubes. Why Specimen Storage Requirements Matter Improper storage can: Kill pathogens Allow contaminating organisms to grow Give false results Examples: Some samples require refrigeration Some must be processed immediately Some must be kept at room temperature When a Specimen Should Be Rejected Common reasons: Improper labeling Leaking container Contaminated sample Wrong container Sample stored improperly Sample received too late Insufficient quantity 3. Media Nonselective Media Supports growth of many different organisms. Example: Nutrient agar Blood agar Purpose: Grow a wide range of bacteria. Selective Media Contains substances that inhibit some organisms but allow others to grow. Example: MacConkey agar (selects for Gram-negative bacteria) Differential Media Distinguishes organisms based on metabolic or biochemical characteristics. Example: MacConkey agar differentiates lactose fermenters vs non-fermenters Colonies change color depending on reaction. 4. Staining Simple Stain Uses one dye to visualize bacteria. Purpose: Observe shape Observe arrangement Example stains: Methylene blue Crystal violet Differential Stain Uses multiple dyes to distinguish between types of bacteria. Example: Gram stain Acid-fast stain Gram Stain Steps and Purpose 1. Crystal Violet (Primary Stain) Stains all cells purple 2. Iodine (Mordant) Forms a complex with crystal violet Helps dye stick to cell walls 3. Alcohol or Acetone (Decolorizer) Removes stain from Gram-negative cells Gram-positive cells retain stain 4. Safranin (Counterstain) Stains Gram-negative cells pink/red Gram Positive vs Gram Negative Gram Positive Bacteria Cell wall: Thick peptidoglycan layer Retains crystal violet Color after stain: Purple Gram Negative Bacteria Cell wall: Thin peptidoglycan Outer membrane present Color after stain: Pink/red 5. Streaking for Isolation (4 Quadrant Method) Purpose To separate individual bacterial cells so they grow into isolated colonies. This allows identification of pure cultures. Steps in Clinical Lab Sterilize loop in flame Obtain bacteria from sample Streak first quadrant Flame loop again Drag bacteria from first quadrant into second Repeat for quadrants 3 and 4 Incubate plate Each quadrant dilutes the bacteria, producing isolated colonies. 6. Streaking for Quantification Purpose To estimate the number of bacteria in a sample. Measured as: CFU = Colony Forming Units Each colony represents one viable bacterium (or group). CFU Calculation Example Formula: C F U / m L = Number of Colonies Dilution × Volume plated CFU/mL= Dilution×Volume plated Number of Colonies ​ Example: 50 colonies 0.1 mL plated 10⁻⁴ dilution C F U / m L = 50 10 − 4 × 0.1 CFU/mL= 10 −4 ×0.1 50 ​ C F U / m L = 5 × 10 6 CFU/mL=5×10 6 7. Immunology Antigen An antigen is a substance that triggers an immune response. Examples: Bacteria Viruses Toxins Foreign proteins Antibody An antibody is a protein produced by B cells that specifically binds to an antigen

Cell theory organisms are composed of 1+ cells, which are the smallest unit of life, which come from pre-existing cells What do Prokaryotic Cells have? - Cell wall - Plasma Cell membrane -Flagella -Ribosomes -Nucleoid Cell Wall made of of carb protein complex, PEPTIOGLYCAN, allows for cell to hold shape Plasma Membrane Controls movement of materials in and out of cells, plays role in binary fission Cytoplasm -occupies interior, no compartmentalization, site of all chemical processes in the cell -Region where organelles can be found Capsule some, not all have this, made of polysaccharide, sticky and allows for attachment to surfaces Pili short hair growth on cell wall, used for attachment, joins bacteria cells to prep for DNA transfer Flagella longer than pili, used for movement Ribosomes where protein synthesis occurs, in big numbers in cells that require high protein content Nucleoid Region non-compartmentalization and has a single long thread of DNA, controls cells and reproduction Plasmids small circular DNA molecules, not connected to main loop Binary Fission the simple cell division, process where DNA is copied and the daughter chromosomes become attached to different regions on the membrane, cell elongates and divides into 2 identical daughter cells Microscope DOs -careful -proper carrying -using for intended purpose Microscope Don'ts -squinting -carrying with one hand -using coarse focus knob on high power -leaving at edge of lab bench Characteristics of Prokaryotic Cells -DNA is circular, not enclosed -Free DNA -Non-membrane bound organelles -70s ribosomes -Very small -Division by binary fission SURFACE AREA TO VOLUME RATIO does what? What does this do? Limits cell size, the bigger this ratio, the more efficient it is for the diffusion to take place in and out of the cell. Differentiation process whereby cells develop into specific cells as a result of the expression of certain genes but not others What are stem cells? Cells that retain their ability to divide into various types of cells. What type of tissue in plants contains stem cells? Meristematic tissue. Where are stem cells found in animals? In embryos. Cytosol Fluid portion of cytoplasm What is the endoplasmic reticulum? An extensive network of tubules and channels that extends almost everywhere from the nucleus to the plasma membrane. What is the function of the endoplasmic reticulum? Transports materials throughout the internal region of the cell. Rough ER has ribosomes on its surface and is therefore involved in protein development and transport. Smooth ER lacks ribosomes on its exterior but contains unique enzymes embedded on its surface. 6 functions of the smooth ER 1. production of membrane phospholipids and cellular lipids 2. Production of sex hormones such as testosterone and estrogen 3. Detoxification of drugs in the liver 4. Storage of calcium ions needed for contraction in muscle cells 5. Transportation of lipid-based compounds 6. Aid the liver in releasing glucose into the bloodstream when needed What are ribosomes? Structures that have no exterior membrane What is the primary function of ribosomes? Carry out protein synthesis What are ribosomes composed of? A type of RNA and a protein How many subunits do ribosomes have? Two subunits What are lysosomes? Intracellular digestive organelles that arise from the Golgi apparatus. What do lysosomes catalyze the breakdown of? Proteins, nucleic acids, lipids, and carbohydrates. Golgi apparatus Responsible for the collection, packaging, modification, and distribution of materials synthesized in the cell Two sides : cis and trans cisternae Golgi apparatus is composed of a stack of flattened sacs called this What shape are mitochondria? Rod-shaped What are mitochondria commonly referred to as? The cell's powerhouse Do mitochondria have their own DNA? Yes, it is similar to that of bacterial cells What type of membrane do mitochondria have? Double-membraned How is the outer membrane of mitochondria described? Smooth What are the folds in the inner membrane of mitochondria called? Cristae matrix Inside the mitochondria inner membrane is fluid called this What is the function of the cristae in mitochondria? The cristae provide a huge internal surface area for the chemical reactions in the mitochondria to occur. What type of ribosomes do mitochondria produce and contain? Mitochondria produce and contain their own ribosomes. What is the primary energy molecule produced by mitochondria? ATP (adenosine triphosphate). What is the nucleus? A compartmentalized region where DNA can be found. What is the nuclear envelope? A double membrane that covers the nucleus. What do the pores in the nuclear envelope allow? Communication with the cell's cytoplasm. What are chloroplasts? Organelles that can only be found in algae and plant cells. What type of membrane do chloroplasts have? Double-membraned. What unique genetic material do chloroplasts contain? Their own ribosomes and DNA in the form of a ring. What structures are found in the interior of chloroplasts? Grana, thylakoids, and the stroma. Granum made up of a stack of thylakoids Thylakoids flattened membrane sacs with components essential for the absorption of light Stroma similar to cytosol; contains many enzymes and chemicals essential to complete the process of photosynthesis What is a centrosome? A structure that consists of a pair of centrioles at right angles to one another. What is the function of centrioles in the centrosome? They are involved in assembling the microtubules necessary for providing structure and movement in the cell. Why are microtubules important for cells? They are necessary for cell division. In which types of cells are centrosomes found? Centrosomes are found in animal, fungal, and most protoctist cells, but not in higher plant cells. What are vacuoles? Storage organelles that usually arise from the Golgi apparatus. What substances do vacuoles store? Potential food, metabolic wastes and toxins, and water. How do vacuoles affect cell size? They allow cells to have a higher surface area to volume ratio even at larger sizes. What role do vacuoles play in plant cells? They allow the uptake of water to provide rigidity to the cell.

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