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31 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What are the postulates of natural selection?
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Variability, Heritability, Variation in reproductive success, Survival/repro is non-random
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What did the pea aphid and desert locust examples illustrate?
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Evironmental conditions inducing variability in phenotypes that IS NOT heritable.
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What does a heritability score of 1 mean?
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A strong parent-offspring correlation. What does it come from?
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The slope of the regression line is 1. Mean parental value trait of parent (x axis) against mean value of phenotype in all of the parents' offspring.
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Chromosome definition
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an organized structure of DNA and protein found in cells. It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences. Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.
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allele definition
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one of two or more forms of a gene or a genetic locus;
Alternate form of a gene |
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genome definition
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the entirety of an organism's hereditary information
-made of DNA or RNA |
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Transcription
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the process of creating a complementary RNA copy of a sequence of DNA
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translation
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the third stage of protein biosynthesis (part of the overall process of gene expression). In translation, messenger RNA (mRNA) produced by transcription is decoded by the ribosome to produce a specific amino acid chain, or polypeptide, that will later fold into an active protein.
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genetic code
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The genetic code is the set of rules by which information encoded in genetic material (DNA or mRNA sequences) is translated into proteins (amino acid sequences) by living cells.
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haploid number
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The haploid number (n) is the number of chromosomes in a gamete. A somatic cell has twice that many chromosomes (2n).
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purine
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A and G
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pyrimidine
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C and T
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polypeptide
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a long, continuous, and unbranched peptide. Peptides are...
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short polymers of amino acid monomers linked by peptide bonds. They are distinguished from proteins on the basis of size,
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What are sources of genetic variation?
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A. Mutation
b. Independent assortment c. Recombination |
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Transition versus transversion
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Types of mutations
-Transitions happen more commonly; less disruptive to DNA replication/protein (A to G; C to T) -Transversions are a purine to pyrimidine change (A to C; G to T) |
this actually isn't as intuitive as I thought. make sure you know.
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Common cause of variability at microsatellites?
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Replication slippage
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Large scale mutation examples
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-Unequal crossing-over (non-homologous recombination
-Inversions; double stranded breaks -Translocations among chromosomes |
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Hardy-Weinberg principle
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-Null model
-What to expect if evolution isn't happening -No change in allele frequencies between generations -HW proportions are restored in a single generation of random mating |
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Assumptions of HW principle
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-No selection
-No migration -No mutation -Large pop size -Random mating (panmixia) |
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What are the four evolutionary "forces"?
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Selection, drift, mutation, migration
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Relative fitness
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"w"
Fitness of genotypes relative to a reference genotype 1 = maximal fitness |
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Selection coefficient
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"s"
s = 1 - w Also represents fitness of genotypes. When no selection against a genotype, w = ___ and s=_____. When genotype is lethal, w=____ and s=_____ |
1, 0
0,1 |
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When selection is for recessive and against a dominant allele...
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Evolution is slow to remove A at first b/c a is hiding in heterozygotes. Removal of A accelerates towards the end.
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When selection is for a dominant and against a recessive allele...
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a will be removed quickly at first, then slower toward the end. This is because some a alleles are hiding in heterozygotes.
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Selection favoring heterozygotes...
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-is termed overdominance
-maintains diversity because one allele will never be fixed (none lost if heteros are favored) -Pop will always evolve to a stable equilibrium maintaining both alleles |
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Freq-dependent selection...
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-maintains diversity in a population
-e.g. rare prey morph undetected by predator; higher fitness until it becomes the common morph; predator learns this new common morph which becomes selected against (decreasing fitness); original common morph re-emerges, driving pop back to equilibrium |
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Mutation...
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-Is weak (slow) evo force
-Can change allele freqs, but over long periods of time -Does not typically change HWP much -Is the ultimate source of genetic variation |
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Hardy-Weinberg take-homes
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1. It's possible to change gt freqs without change in allele freqs
2. HW equil does NOT mean p=0.5 and q-0.5 3. Deviation from HWP is a weak test of evolution -Lack of deviation doesn't necessarily mean no evolution -Conversely, if there is deviation, good chance that something interesting is going on. 4. HWP proportions will be restored in a single generation of random mating! So it can be used to calculate next generation gt freqs after selection, migration, etc. |
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Selection take-homes
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Mutation take-homes
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A "weak" force in terms of rate of evolution, but...
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the ULTIMATE source of variation: without new mutations, evo can eventually grind to a halt. Lack of variation = no evolution.
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Migration (aka "________") is...
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"gene flow"
Movement of alleles between populations |
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