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75 Cards in this Set
- Front
- Back
Transcription |
The synthesis of RNA from a DNA template |
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RNA Polymerase |
Responsible for synthesis of RNA |
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Holoenzyme |
-RNA is a core enzyme that binds to sigma -Sigma recognizes and binds to the promoter |
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RNA Splicing |
-snRNPs edit mRNA in the nucleus and excise introns(noncoding sections of RNA transcript) -Splice the exons(code for proteins) together to form edited mRNA |
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Adding Caps and Tails to RNA Transcripts |
-Addition of 5' cap -Addition of a poly(A) tail -Importance of this process: ---Prevents premature degradation by enzymes ---Increased amounts of translated protein ---Checking mechanism for nuclear export |
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Transcription and Translation |
occur simultaneously in bacteria (both processes occur in the cytosol in bacteria) |
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mRNA in Eukaryotes |
Must be exported from the nucleus to the cytosol for translation |
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tRna is an adapter molecule |
-Amino acids are brought to the ribosome by transfer RNA molecules --Anticodon region that recognizes an mRNA codon via base pairing --tRNA is charged with an amino acid at the 3' end (aminoacyl tRNA synthestase) |
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E Site |
Holds a tRNA that will exit |
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P Site |
Holds a tRNA with growing polypeptide attached |
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A Site |
Holds an aminoacyl tRNA |
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Initiation of Translation |
-Initiation proteins manage assembly of ribosomes and mRNAs -mRNA binds to small subunit --Ribosome binding sequence on mRNA (Shine-Dalgarno sequence) |
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Elongation of Polypeptide During Translation |
1) Incoming aminoacyl tRNA 2) Peptide-bond formation 3) Translocation Repeats itself another three times |
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Terminating Translation |
Meditated by proteins called release factors (looks like tRNAs, binds tightly to the A site) 1) Release factor binds to stop codon 2) Polypeptide and uncharged tRNAs are released 3) Ribosome subunits seperate |
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Evolution is a property of life |
The theory of evolution by natural selection ranks alongside other scientific theories -Copernicus theory of the sun as the center of our solar system -Newtons law of motion and theory of gravitation -Germ theory of disease -Chromosomal theory of inheritance -Theory of plate tectonics -Einstein's theory of relativity |
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Evolution by Natural Selection |
Ideas of Wallace and Darwin challenged explanations of the diversity of life -leading explanation of diversity at the time was special creation -Special creation asserts that: 1) All species are unrelated 2) Life on Earth was ~6000 years ago 3) Species are incapable of change |
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Wallace and Darwin were the first to use scientific principles in their explanation of diversity of life |
Two components: 1) Pattern component (a statement that summarizes a series of observations about the natural world) 2) Process component (a mechanism that produces that pattern or set of observations) |
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Evolutionary Thought |
Wallace and Darwin were not the first evolutionary thinkers: 1) Aristotle 2) Plato 3) Jean-Baptiste Lemark |
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Wallace and Darwin changed evolutionary thought |
1) Species are dynamic and can change over time 2) Replaced typological thinking with population thinking 3) Evolution by natural selection was testable through experimentation (Species change through time and are related through a common ancestry) |
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Extant |
Currently living |
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Transitional Features |
Tetrapod Limb -Tulerpeton (362 mya) -Tiktaalik (375 mya) -Acanthostega (365 mya) -Eusthenopteron (385 mya) |
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Vestigal Traits |
Reduced Versions of traits in other species |
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Biogeography |
Closely related species often live in the same geographic area |
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Homology |
Similarity that exists between species because they inherited the trait from a common ancestor |
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Genetic Homology |
Pax6 is homologous gene in the mouse (similar gene in other species) -Modified in each lineage ex:Aniridia (Human) without iris Fruitflies (eyeless) |
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Developmental Homology |
Structures that appear early in development are similar (embryology) |
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Structural Homology |
Structures that are similar in adult morphology |
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Evidence for Evolution |
Prediction 1: Species are not static, but change through time Prediction 2: Species are related, not independent |
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Evolution produces a tree of life |
Bacteria--Archae--Flowering Plants--Mosses--Tapeworms--Vertebrates--Fungi |
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Four Mechanisms that alter allele frequencies in a population |
1) Natural Selection: Increases frequency of alleles that contribute to reproductive success in a particular environment 2) Genetic Drift: Causes allele frequencies to change randomly 3)Gene Flow: Addition/deletion of alleles in a population of breeding individuals by migration/immigration 4) Mutation: Modifies allele frequencies by continually introducing new alleles |
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Hardy-Weinberg Principle (Cannot have any of the four mechanisms) |
Acts as a null hypothesis when we want to know whether evolution is occuring at a particular gene -Genotype frequency: p2+2pq+q2 -Allele frequency: p+q=1 |
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Directional Selction |
Favors one extreme phenotype cause the average value of a trait to change -Genetic variation is reduced |
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Stabilizing Selection |
Favors phenotype near the middle of the range and reduces the amount of variation in a trait -genetic variation is reduced |
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Disruptive Selection |
Increase the amount of variation in a trait -Genetic variation is increased |
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Balancing Selection |
No single phenotype is favored in all populations -Genetic variation is maintained |
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Genetic Drift |
Changes in allele frequency as a result of random events -Random with respect to fitness -Most pronounced in small populations -Over time can lead to the random loss or fixation of allele |
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Founder Effect |
New population is likely to have different allele frequencies than the source population by chance |
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Genetic bottleneck |
Bottleneck population is likely to have different allele frequencies than original population by change |
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Gene Flow |
Movement of alleles from one population to another |
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Mutation |
-Mutation increases genetic diversity in populations (Random) -Mutation does not occur enough to make it an important factor in changing allele frequencies |
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Nonrandom mating |
Hardy-Weinberg principle is based on random, chance matings, however in nature matings may not be random with respect to the gene in question |
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Interbreeding |
Mating between relatives (increase homozygosity) |
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Sexual Selection |
Occurs when individuals within a population differ in their ability to attract mates -choosy females -male-male competition |
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Sexual Dimorphisms |
Sexually dimorphic traits are those that vary between males and females -results from sexual selection |
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Species |
An evolutionary independent population or group of populations Three Criteria: Biological Species Morphospecies Phylogenetic |
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Biological Species Concept |
Populations are evolutionarily independent if they do not interbreed -Populations are reproductively isolated -Pre-zygotic barriers (prevents individuals from mating/breeding) --Temporal, habitat, behavioral, gametica, mechanical -Post-zygotic barriers (Offspring from mating between individuals of different species do not survive (or reproduce) --Hybrid viability, Hybrid sterility |
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Temporal |
populations are isolated because they breed at different times |
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Habitat |
populations are isolated because they breed in different habitats |
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Behavioral |
Populations do not interbreed because their courtship displays differ |
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Gametic Barrier |
Matings fail because eggs and sperm are incompatible |
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Mechanical |
Matings fail because male and female reproductive structures are incompatible |
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Hybrid viability |
Hybrid offspring do not develop normally and die as embryos |
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Hybrid Sterility |
Hybrid offspring mature but are sterile as adults |
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Morphospecies Concept |
Based on features associated with size or shape of other physical differences |
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Phylogenetic Species Concept |
Identifies evolutionarily independent lineages based on reconstructing an evolutionary history of a population |
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Allopatric Speciation |
Genetic isolation that happens routinely when populations become physically separated |
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Sympatric Speciation |
Speciation events that take place in the same geographical area -No physical barrier that prevents interbreeeding |
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What happens when two populations that had been isolated come into contact and there are no prezygotic reproductive barriers in place? |
1) Fusion 2) reinforcement 3)Hybrid zones 4) Extinction of one population 5) Development of a new species |
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Fusion of the population |
Two populations freely interbreed (when same species come in contact) |
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Reinforcement of divergence |
Hybrid offspring have low fitness, natural selection favors the evolution of traits the prevent interbreeding between the populations |
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Hybrid zone formation |
Hybridization occurs in a well-defined geographic area. This area may move over time or be stable |
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Extinction of one population |
One population or species is a better competitor for shared resources, then the poor competitor may be driven to extinction |
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Creation of new species |
Combination of genes in hybrid offspring allows them to occupy distinct habitats or use novel resources, they may form a new species |
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Homology |
Similarity in organisms due to common ancestry |
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Monophyletic group |
Evolutionary unit that includes an ancestral population and all of its descendants but no others (also called a lineage, or clade) |
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Synapomorphy |
A shared, derived trait |
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Homoplasy |
Similarity in organisms due to reason other than common ancestry |
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Polyphyletic group |
An unnatural group that does not include the most recent common ancestor |
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Paraphyletic group |
A group that includes an ancestral population and some of its descent but not all |
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Habitat Bias (Limitations of fossil record) |
Areas where sediment is actively being deposited, organisms are more likely to fossilize |
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Taxonomic and Tissue Bias (limitations of fossil record) |
Organisms with hard shells, bones, or casing are more likely to fossilize |
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Temporal Bias (Limitations) |
Recent fossils are more common than ancient fossils |
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Abundance bias (limitations) |
Widespread, abundant, or long-lived organisms are represented in the fossil record more often |
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Phanerozoic Eon is divided into three eras: |
Paleozoic, Mesozoic, and Cenozoic |
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Each of these are a further divided |
Periods and Epochs |