Science slay

DNA/RNA/PROTEIN SYNTHESIS: 

MUST KNOW:

• The Structure of DNA

• DNA Replication

• RNA

• Ribosomes and Protein Synthesis

• Mutations

  • DNA and RNA are nucleic acids

  • Both are made of nucleotides, which are comprised of a sugar, phosphate, nitrogenous base

DNA – deoxyribonucleic acid 

  • Double helix 

  • Deoxyribose sugar 

  • Adenine, thymine, cytosine, and guanine 

  • In the nucleus of eukaryotes 

  • Fact: human DNA is 3 billion nucleotides long 

Structure: 

  • Nucleotides link together to form long chains 

  • nitrogenous bases match in the middle to form a two stranded molecule 

  • Sugar and phosphate are on the outside backbone 

 

RNA – Ribonucleic acid

  • Single stranded 

  • Ribose sugar 

  • RNA helps DNA make proteins

  • there are 3 types:

  •  mRNA- messenger RNA

  • rRNA- ribosomal RNA

  • tRNA- transfer RNA

  • nitrogenous bases include adenine, uracil, cystine and guanine

  • In the nucleus and cytoplasm

Base Pairing Rules:

  • A(adenine) pairs with T (Thymine)

  • C (Cytosine) pairs with G (gyuamine)

  • In RNA A(adenine) pairs with U (Uracil)

  • The pairs are held together by hydrogen bonds

THE HISTORY OF DNA: 

Griffith’s Experiments: 

  • Griffith concluded that something from the heat killed bacteria “transformed” the harmless bacteria and made them lethal 

  • Transformation – the process by which cells take DNA molecules from their external environment through the cell wall, this DNA is then either integrated into the recipients genome or replicated as an independent plasmid within the cell 

Bacteriophage – a type of virus that infects and kills bacteria  

Hershey & Chase: 

  • put radioactive elements on both proteins and the DNA of the virus

  • Kate’s Memory: Hershey puts radioactive elements in candy to make it unhealthy Chocolate- unhealthy- unhealthy- radioactive 

Chargaff’s rule:

  • Erwin Chargaff discovered that the percentage of adenine and thymine bases are almost equal in any sample of DNA (same for guanine and cytosine) 

Rosalind Franklin: 

  • Used a technique called x- ray diffraction to study the structure of DNA

  • Photo 51, this image was a gamechanger and proved DNA is in the shape of a helix 

  • Kate’s Memory: franklin- Frankenstein- Frankenstein- broken- broken body parts are scanned by x rays

Watson & Crick:

  • Used Rosalind Franklin’s image and built a model explaining specifics of DNA structure 

  • Memory: Crick used Franklin’s pic 

DNA REPLICATION 

  • Whenever cells divide (mitosis) DNA must be copied

  • DNA replication – the process of making a copy of the original DNA, happens during S phase in interphase (Synthesis) 

  • Semiconservative – replication uses an existing DNA as template, each DNA molecule consists of an original and new strand 

Enzymes: 

  • Proteins 

  • 3 types: 

    • Helicase – separates DNA strands 

    • DNA polymerase – adds nucleotides and proofreads 

    • Ligase – links new pieces of DNA 

Bonding: 

  • DNA strands are held together by hydrogen bonds (weak) 

  • Replication always occurs in the 5’ to 3’ direction 

Transcribe – DNA-RNA 

Translate – RNA-AA 

  • Central Dogma – DNA → RNA → Protein, explains how life is determined through DNA 

PROTEIN SYNTHESIS – process of making proteins 

  • 2 steps: 

    • Transcription – mRNA copies DNA’s instructions 

    • Translation – ribosomes use mRNA to make proteins 

Transcription: 

  • Nucleus 

  • DNA and mRNA 

  • DNA unwinds where the gene is, RNA polymerase uses DNA as a template to make an mRNA copy (transcript), now the mRNA can leave the nucleus 

Genetic Code

  • mRNA has codons 

  • Codon – a sequence of 3 nucleotides that code for an amino acid (monomer of proteins) 

 

RNAs: 

  • mRNA – messenger, carries DNA message as codons 

  • rRNA – ribosomal, makes up ribosomes 

  • tRNA – transfer, matches anti-codon to mRNA codon to bring correct amino acid 

Translation: 

  • Ribosome 

  • mRNA, ribosome, tRNA 

  • mRNA finds a ribosome and binds to it, mRNA codons are read by tRNA, tRNA brings in the right amino acid that matches the codon, amino acids link together to form a protein 

MUTATIONS – mistakes that occur in the DNA or RNA that lead to variation in a population  

  • A change in an organisms nucleic acids 

  • 2 types: 

    • Gene – genetics 

    • Chromosomal – heredity 

Gene Mutations: 

  • Point Mutation – substitution 

    • a mutation in which one nucleotide is put in place of the correct nucleotide 

    • Usually this mistake can be caught and fixed by DNA polymerase 

    • If not, the substitution might permanently change an organism’s DNA 

    • Ex: Sickle cell anemia 

  • Frame Shift Mutation – insertion or deletion 

    • Insertion or deletion of a nucleotide shifts the entire sequence by one or more nucleotides 

    • Bigger impact than point mutation 

    • Ex: Cystic fibrosis 

Mistakes Happen: 

  • Missense mutation – when a substitution affects the protein folding 

    • Ex: AAG (Lys) → CAG (Glu) 

  • Nonsense mutation – when a substitution results in a premature stop codon 

    • Ex: UAC (Tyr) → UAA (STOP) 

  • Silent mutation – when a substitution has no effect 

    • Ex: AAG (Lys) → AAA (Lys) 

Mutation Factors: 

  • Replication errors 

  • Mitosis 

  • Meiosis 

  • Protein synthesis 

  • Mutations are not uncommon, organisms have many tools to repair them 

    • Like DNA has a build in proof-reader, DNA polymerase 

Mutagens – factors that can lead to mutations 

  • Ultraviolet

  • Industrial chemicals 

  • Carcinogens 

  • Infectious agents (viruses and bacteria) 

EVOLUTION: 

  • Darwin and his discoveries 

  • Natural selection 

  • Evidence for evolution 

  • Mechanisms for evolution 

Intro: 

– Evolution happens to populations over time 

– diversity = the variety of living things that inhabit our planet 

– Endosymbiotic theory = proposed that organelles of eukaryotic cells were once prokaryotic cells that have been engulfed by a larger prokaryotic cell (one theory of how life began) 

– Evolution = a change in the inherited characteristics of a group of organisms over generations, a heritable change in the characteristics of a population from one generation to the next  

– Evolutionary theory = the collection of scientific facts, observations, and hypotheses that attempt to explain the diversity of life 

– much of today’s understanding of evolution was Darwin’s work, but Darwin did not come up with the idea of evolution himself, many other scientists contributed to his work  

– Jean-Baptiste Lamarck – a french naturalist, put forward his own theory of evolution: organisms inherited changes caused by use or disuse in its parents 

– Alfred Russel Wallece – british naturalist, co-discoverer of the theory of evolution 

Darwin: 

  • Adaptations seen in certain organisms would not been seen on a different island 

  • Adaptations – characteristics of organisms that enhance their survival and reproduction in specific environments 

  • Variation – differences in traits among organisms 

  • Fossils – preserved remind of an ancient organism 

  • Began his voyage thinking that species could not change 

  • Natural Selection – a mechanism by which individuals that have inherited beneficial adaptations produce more offspring, organisms with the the best traits will survive and reproduce, survival of the fittest, acts on phenotypes (physical traits) four main principles: 

    • Variation – heritable differences that exist in every population 

    • Overproduction – species tend to produce more offspring than the environment can support, results in competition for resources 

    • Adaptation – a certain variation allows an organism to survive better than other organisms 

    • Descent with modification – over time natural selection will result in species with adaptations that are well suited to their environment, certain traits become more common in a population 

Evidence of Evolution : 

  • Embryology - the study of embryos and their development, similarity suggests evolution from a distant common ancestor  

  • Paleontology - the study of fossils or extinct organisms 

    • Relative dating - estimating the age of a fossil 

    • Absolute dating - C-14 dating, calculating the age of a fossil

  • Biogeography - the study of the distribution of organisms around the world 

  • Morphology - the branch of biology that deals with the form of living organisms and relationships between their structures, comparative anatomy 

    • Homologous - similar structure but different function, suggests common ancestor, ex: human and cat arm 

    • Vestigial - leftover structure that used to have a function in a previous ancestor, ex: appendix 

    • Analogous - different structure but same function, does not suggest common ancestor, ex: bat and bird wing 

  • Biochemistry - similarities between organisms on the molecular level, DNA and protein sequences 

Population Genetics: 

  • Demonstrates how genetics and evolution influence one another 

  • Population – all the individuals of a species that live in the same area, smallest unit that evolution occurs  

  • Species – group of organisms so similar that they can breed and produce fertile offspring 

  • Gene Pool – used to describe the total genetic information available in a population 

  • Allele Frequency – the number of times that one allele occurs in a gene pool compared to other alleles, # allele/total # of alleles 

  • Evolution – any change in the relative frequency of alleles in a population, result of changes in the gene pool 

  • If allele frequency does not change, a population will not evolve 

  • Hardy Weinberg Genetic Equilibrium – describes a hypothetical population that is not evolving 

    • Population is very large 

    • No migration 

    • No mutation 

    • Random mating 

    • No natural selection

  • Five mechanisms of change in the allele frequency:

    • Mutations – ultimate source of new variations, change in the nucleotide sequence

    • Gene Flow – movement of alleles in or out of a population as a result of migration, Immigration - into, Emigration - out 

    • Genetic Drift – a series of chance occurrences, natural disasters, ignores adaptations, loss of diversity 

    • Nonrandom Mating – choosing mates to reproduce with, amplification of certain traits, decreases diversity 

    • Natural Selection – only cause of evolution that adapts a population to its environment 

Classifying Organisms: 

  • Linnaean System of Classification – 7 levels that organisms are classified into 

  • Taxonomy – branch of biology that deals with grouping and naming organisms based on their physical similarities 

  • Scientific name – genus and species (ex: Canis lupus = grey wolf, Canis familiaris = domestic dog) 

    • Genus – always capitalized, implies relation 

    • Species – always lowercase, a description 

Domain – bacteria, archaea, eukarya 

  1. Kingdom 

  2. Phylum 

  3. Class 

  4. Order 

  5. Family 

  6. Genus 

  7. Species 

  • Phylogenetic Trees = diagram used to predict evolutionary relationships between groups of organisms 

    • Branch points/nodes – shows a species diverging from a common ancestor (speciation) 

    • Tips/terminal nodes – represents current organisms 

    • Root – shows a common ancestor

  • Cladogram – an evolutionary tree that suggests how species may be related 

    • Hash marks – derived characters 

    • Clades – snip rule, whenever you snip a branch that clade falls off 

– The drought conditions on the islands may cause a decrease in the finch population over time. Due to the drought, there will be harder seeds. With limited resources, the finch population will adapt to have bigger/stronger beaks to eat the harder seeds. Natural selection would select for stronger beaks and the smaller beaked birds will not survive. Over time, the finch population will evolve to have bigger beaks because that is the beneficial trait. The stronger beaked finch population will increase over time. 

– Adaptation = bigger/stronger beaks 

– Natural Selection = choose for bigger or smaller and leads to survival and reproduction 

– Evolution = big picture, bigger beak population will increase 

ECOLOGY 

Must Know: 

  • Energy, Producers, and Consumers 

  • Energy Flow in Ecosystem 

  • Cycles of Matter 

  • Species Interactions 

Notes on board: 

Biosphere, biome, ecosystem, class, population, organism 

Symbiosis (mutualism, parasitism, commensalism) 

Keystone species, and catastrophe thing 

Niche 

Limiting factors → carrying capas=city 

Food web vs food chain 

Burning fossil fuels, cellular respiration, waste, volcanic eruptions → carbon 

Migration (immigration, immigration ) 

Logistic vs exponential 

Br, dr, LE 

Sustainability 

Abiotic vs biotic 

Energy pyramid   

Intro: 

Levels of Organization: 

  • Biosphere – parts of Earth where life exists 

  • Biome – group of ecosystems within a similar climate (ex: rainforest) 

  • Ecosystem – all living and nonliving things in an area (ex: lake) 

  • Community – all various populations that interact 

  • Population – group of the same species living in the same area 

  • Species – all similar organisms that can produce fertile offspring 

  • Ecology – the study of the interactions among organisms and their environments 

  • Abiotic – non-living 

  • Biotic – living 

  • Biodiversity – variety of organisms in an ecosystem 

  • Organism – any living thing within an ecosystem 

  • Habitat – place where an organism obtains food, shelter, moisture, and temperature levels that it needs 

  • Niche – unique role or job of an organism in its ecosystem 

  • Energy flow – transfer of energy between organisms throughout an ecosystem 

  • Energy pyramid – shows the direction that energy flows 

    • Trophic level – each level on the pyramid 

    • Producers – at the bottom, make their own food 

    • Consumers – need to consume other organisms for energy, primary, secondary, and tertiary 

    • Decomposers – return nutrients to the soil by consuming waste and dead organisms 

  • Symbiosis – close relationships organisms have with each other in an ecosystem 

    • Mutualism – both benefit, ex: bees and flowers 

    • Parasitism – one is helped one is harmed, ex: tics and humans 

    • Commensalism – one benefits and one is neutral, ex: whale and barnacle 

Population: 

  • Population – a group of individuals that belong to the same species that live in the same area at the same time 

  • Population size – the number of individuals in the population 

  • Geographic distribution – range of the population 

  • Population density – the number of individuals per unit area 

  • Population sample – can be conducted to determine the the population density of a species 

  • Population growth factors: Birth rate, death rate, and life expectancy 

  • Growth rate – the amount by which a population’s size changes over a given period of time 

    • Factors: number of births, number of deaths, immigration/emigration 

Exponential v.s. Logistic: 

  • Exponential growth – describes a population that is increasing rapidly, the larger the population gets the faster it grows, J-shaped curve 

    • Populations cannot grow exponentially for very long 

  • Limiting factor – any factor that restrains population growth 

    • Space to grow, food, water, predation, competition, human disturbances, oxygen  

  • Carrying capacity – the number of individuals the environment can support over a long period of time

  • Limiting factors determine carrying capacity 

  • Logistic growth – describes a population in which growth slows or stops following exponential growth 

Keystone species – an organism that helps define an entire ecosystem, without it the whole ecosystem would change (ex: sea otters, starfish, bees) 

Trophic cascade – a series of change in the trophic levels of the energy pyramid resulting from the removal of a keystone species 

Biogeochemical Cycles:

  • Energy starts with the sun 

  • Producers/autotrophs rely on the sun’s energy, water, and carbon dioxide to create glucose and oxygen (photosynthesis)  

  • Consumers/heterotrophs use that oxygen and glucose and place carbon dioxide and water back into the atmosphere 

  • Sun → producers → consumers → decomposers 

  • Energy exits the ecosystem in the form of heat which cannot be recycled 

  • Organisms need energy as well as nutrients (water, minerals) to survive 

  • For most organisms, more than 95% of the body is make up of carbon, hydrogen, oxygen, and nitrogen 

  • Energy cannot be recycled; matter can be recycled between ecosystems 

  • Biogeochemical cycle – the process by which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one part of the biosphere to another 

Carbon Cycle: 

  • Carbon is the key element of all organic compounds (macromolecules) 

  • Carbohydrates, lipids, proteins, and nucleic acids all contain carbon 

  • Photosynthesis and cellular respiration form the basis of the carbon cycle 

  • Photosynthesis – carbon dioxide is removed from the atmosphere by plants and used to build molecules of glucose 

  • Cellular respiration – returns carbon dioxide back into the atmosphere (animals, plants, fungi, and protists) 

  • Carbon moves through an ecosystem in other ways too: 

    • Geochemical processes – erosion and volcanic activity release carbon dioxide into the atmosphere and oceans 

    • Biogeochemical processes – cause dead organisms to decay under pressure; their bodies are converted to fossil fuels, stores carbon underground 

    • Human activities – mining, cutting and burning forests, and burning fossil fuels release carbon dioxide into the atmosphere 

  1. Carbon is present in the atmosphere in the form of carbon dioxide 

  2. This carbon dioxide is released to the atmosphere by cellular respiration, volcanic activity, burning of fossil fuels, and by the decomposition of organic matter 

  3. Plants take in the carbon dioxide and use it during photosynthesis to build molecules of glucose (C6H12O6) 

  4. The glucose molecules and other carbohydrates are used by consumers 

  • This cycle threatens biodiversity 

** look at past tests, kahoots