Term
ANSWERS: MOLECULAR GENETIC BASIS OF EVOLUTION
What are the four nitrogenous bases in DNA? |
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Definition
| Cytosine, Adenine, Guanine, and Thymine |
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Term
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Definition
| nitrogenous base + pentose sugar (deoxyribose) + phosphate group |
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Term
| How are the two polynucleotide strands held together in the DNA double helix? |
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Definition
| By hydrogen bonds between the two nitrogenous bases. |
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Term
| What is the pattern of complementary base pairing in DNA? |
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Definition
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Term
| What does antiparallel mean in the context of the two polynucleotide strands of DNA? |
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Definition
| One strand runs the 5' to 3' direction while the other strand runs in the 3' to 5' direction. |
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Term
| To which end of each growing strand are nucleotides added in DNA replication? |
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Definition
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Term
| What is the replication complex? |
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Definition
| A protein that binds to the DNA template at the origin of replication. |
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Term
| What is an origin of replication? |
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Definition
| A specific sequence of bases along the DNA that mark the start of DNA replication |
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Term
| What is the replication fork? |
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Definition
| The rift/split caused in the middle of DNA molecule caused by the fact that DNA is replicated in both directions. |
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Term
| What is the function of DNA polymerase? |
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Definition
| They unwind the DNA template and synthesize new nucleotides in the 5' to 3' direction. |
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Term
| What are the leading and lagging strands? How does replication differ on the leading and lagging strands? What is the role of Okazaki fragments? |
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Definition
| One strand which grows continuously and is called the leading strand while the other strand is grown in short discontinuous stretches called Okazaki fragments. |
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Term
| What does the proofreading function of DNA polymerase accomplish? |
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Definition
| Proofreading DURING replication ensures that DNA replication occurs with very high accuracy by checking for any mispaired bases. |
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Term
| What is the function of mismatch repair proteins in DNA replication? |
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Definition
| They're the second level of proofreading. They check for errors AFTER replication. If errors are found, they excise them, and DNA polymerase comes in and rematches them. |
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Term
| What are transcription and translation? |
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Definition
Transcription: a creation of a RNA sequence from a DNA sequence
Translation: converts mRNA sequence into amino acid sequence of a polypeptide with help from tRNA and ribosomes in the cytoplasm. |
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Term
| How does RNA differ from DNA? |
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Definition
1. 1 polynucleotide strand
2. Ribose instead of deoxyribose
3. Uracil (U) instead of thymine (T) |
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Term
| What is the function of RNA polymerase? |
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Definition
| RNA adds nucleotide sequences to the 3' end of the DNA template during transcription. |
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Term
| How do initiation, elongation, and termination occur during transcription? |
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Definition
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Term
| What is a promoter in the context of transcription? |
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Definition
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Term
| Is the RNA transcript antiparallel to the DNA template strand? |
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Definition
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Term
| If so, what does this mean? |
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Definition
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Term
| What is the genetic code (in general terms)? |
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Definition
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Term
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Definition
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Term
| What do the codons UUU, UCU, UCG, CCG, and GGG specify in terms of amino acids? |
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Definition
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Term
| What do the codons AUG and UAG specify? |
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Definition
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Term
| What makes the genetic code redundant? |
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Definition
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Term
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Definition
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Term
| What is transfer RNA and how does it function in translation? |
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Definition
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Term
| What is a tRNA anticodon? |
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Definition
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Term
| If the DNA sequence on the template strand is 3’-TAG-5’, what is the anticodon, and what amino acid is bound by the tRNA when it is charged? |
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Definition
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Term
| How do initiation, elongation, and termination occur in translation? |
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Definition
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Term
| What is an initiation complex? |
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Definition
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Term
| What amino acid is the first one in the polypeptide sequence (as specified by the start codon)? |
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Definition
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Term
| What is a release factor in translation? |
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Definition
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Term
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Definition
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Term
| What is mRNA processing in eukaryotes? |
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Definition
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Term
| What are exons and introns? |
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Definition
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Term
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Definition
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Term
| How do spliceosomes work? |
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Definition
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Term
| What are snRNPs, and what is their function? |
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Definition
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Term
ANSWERS: ORIGIN AND FATE OF ALLELES IN POPULATIONS
What are germ line mutations and somatic mutations? |
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Definition
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Term
| What are point mutations? |
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Definition
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Term
| By what three mechanisms might errors arise in DNA replication, thereby leading to point mutations? |
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Definition
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Term
| What is the difference between a spontaneous mutation and an induced mutation? |
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Definition
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Term
| What are transitions and transversions, and which of the two are typically more common? |
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Definition
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Term
| What is the Hardy- Weinberg law, or Hardy-Weinberg equilibrium? |
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Definition
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Term
| What four special conditions are necessary for the Hardy-Weinberg equilibrium to exist in a population? |
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Definition
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Term
| For a single gene locus with two alternate alleles in a population under Hardy-Weinberg equilibrium, how do you calculate the genotypic frequencies if you are given the allelic frequencies? |
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Definition
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Term
| How do you calculate the allelic frequencies if you are given the genotypic frequencies? |
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Definition
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Term
| What are homozygotes and heterozygotes? |
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Definition
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Term
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Definition
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Term
| What are the four key mechanisms of evolution in natural populations? |
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Definition
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Term
| How are the four mechanisms of evolution related to the four conditions underlying the Hardy-Weinberg equilibrium? |
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Definition
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Term
ANSWERS: SELECTION AND QUANTITATIVE TRAITS
What is selection? |
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Definition
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Term
| How is selection related to differences in viability or fertility? |
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Definition
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Term
| What is fitness in the context of selection? |
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Definition
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Term
| How important is natural selection in natural populations? |
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Definition
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Term
| What relevance, if any, does the process of mutation have in terms of natural selection? |
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Definition
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Term
| What evidence do the classic laboratory experiments with the fruit fly, Drosophila melanogaster, provide for the operation of selection? |
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Definition
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Term
| What determined the differences in fitness in the experimental populations of D. melanogaster? |
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Definition
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Term
| Have similar results been obtained for other characteristics in Drosophila? |
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Definition
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Term
| Do medium ground finches on Daphne Major Island exhibit variation in beak depth? |
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Definition
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Term
| Is there evidence that the variation is genetically based? |
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Definition
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Term
| What happened to the finch population and its food supply during the severe drought of 1977? |
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Definition
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Term
| Following the severe drought, how did mean beak depth in the population of surviving finches compare to that before the drought? |
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Definition
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Term
| What additional evidence did the Grants and their students provide that natural selection occurred in the finch population? |
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Definition
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Term
| What is a quantitative trait? |
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Definition
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Term
| How can we distinguish the influence of genes from that of the environment for quantitative traits? |
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Definition
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Term
| How is heritability calculated? |
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Definition
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Term
| What is implied by a heritability of 1, a heritability of 0, and a heritability of 0.5? |
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Definition
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Term
| What factor can confound the calculation of heritability using the relationship between quantitative trait values in parents and their offspring? How? |
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Definition
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Term
| What experimental design can reduce or eliminate the influence of the confounding factor? |
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Definition
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Term
| What results were obtained for beak depth in song sparrows when the latter experimental design was followed? |
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Definition
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Term
| What is the selection differential, and how was it calculated in the hypothetical selective breeding experiment on tail length in mice? |
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Definition
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Term
| What is the response to selection (r) and what is its relationship to heritability (h) and the selection differential (s)? |
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Definition
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Term
| How was the response to selection calculated in the hypothetical selective breeding experiment on tail length in mice? |
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Definition
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Term
| What are directional and stabilizing selection? |
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Definition
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Term
| What feature of birth weights in humans is likely to lead to stabilizing selection? |
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Definition
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Term
ANSWERS: DRIFT, MIGRATION, AND MUTATION
What is genetic drift? |
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Definition
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Term
| What is the relationship between genetic drift and sampling error? |
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Definition
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Term
| Under what circumstances is genetic drift likely to occur in nature? |
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Definition
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Term
| Why does genetic drift usually result in fixation of a single allele at a given locus over time? |
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Definition
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Term
| Over 100 generations, what happens to average heterozygosity in populations of size 4, 40, and 400? |
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Definition
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Term
| With genetic drift, what is the relationship between loss of genetic variation and effective population size? |
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Definition
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Term
| What is the quantitative relationship between effective population size and the numbers of breeding females and males in a population? |
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Definition
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Term
| What other factor influences effective population size, as discussed in lecture? |
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Definition
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Term
| What is the relationship between redundancy in the genetic code and synonymous mutations? |
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Definition
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Term
| What are nonsynonymous mutations? |
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Definition
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Term
| Can you identify examples of each (different from those discussed in lecture)? |
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Definition
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Term
| At which position in the codons do most (but not all) synonymous mutations occur? |
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Definition
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Term
| At which positions in the codons do most nonsynonymous mutations occur? |
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Definition
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Term
| Which types of point mutations are likely to be selectively neutral and why? |
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Definition
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Term
| Which types of point mutations are likely to be deleterious, and what is their likely fate in terms of selection? |
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Definition
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Term
| Which types of point mutations may be advantageous, and what is their likely fate in terms of selection? |
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Definition
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Term
| What are two key predictions (or expectations) of the Neutral Theory of Molecular Evolution? |
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Definition
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Term
| The Neutral Theory further states that the number of neutral mutations that arise per generation and are likely to become fixed is constant, with a value equal to the neutral mutation rate. Can you explain why in mathematical terms? |
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Definition
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Term
| Is there evidence to support the Neutral Theory? |
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Definition
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Term
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Definition
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Term
| How does the Da/Ds ratio differ if nonsynonymous substitutions are neutral, deleterious, or advantageous? |
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Definition
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Term
| What pattern in Da/Ds ratios did Huttley and colleagues find for the BRCA1 gene in mammals, and what were their main inferences? |
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Definition
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Term
| For what other genes has evidence for positive selection been documented? |
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Definition
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Term
| Are there underlying reasons why one might expect genes such as those that encode for MHC proteins in humans to experience positive selection? |
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Definition
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Term
| What is gene flow (or differential migration)? |
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Definition
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Term
| How important is evolution by mutation acting alone in natural populations? |
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Definition
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