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.

Photosynthesis

The process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll.

Cell respiration

The metabolic process in which cells convert glucose and oxygen into energy, carbon dioxide, and water.

Mitochondria

The organelles in eukaryotic cells that produce energy through the process of respiration and regulate cellular metabolism.

Chlorophyll

The green pigment found in plants that is responsible for the absorption of light to provide energy for photosynthesis.

ATP (Adenosine Triphosphate)

The primary energy carrier in all living organisms, providing energy for many cellular processes.

Ecosystem

A biological community of interacting organisms and their physical environment.

Biodiversity

The variety of life in the world or in a particular habitat or ecosystem.

Food chain

A linear sequence of organisms through which nutrients and energy pass as one organism eats another.

Mutation

A change in the DNA sequence of an organism, which can lead to changes in traits or the creation of new traits.

Natural selection

The process whereby organisms better adapted to their environment tend to survive and produce more offspring.