Exam 23: Evolution of Genes and Genomes

Transcription factors are proteins that bind specific DNA sequences to regulate gene transcription.Some families of transcription factors bind zinc molecules to form structural motifs called zinc fingers, which facilitate binding to the DNA.Transcription factors that have the so-called classical zinc finger motif bind each zinc molecule via two cysteine and two histidine amino acids.When comparing the orthologs of these genes in closely related species, one would expect to find that the position and conservation of the cysteine and histidine amino acids in the compared sequences are

Why can lateral gene transfer be advantageous to a species?

When researchers apply the principles of evolution to produce new molecules that can be used for pharmaceuticals, they are

Refer to the figure. What is the correct order of sequence numbers in the top row of the similarity matrix?

Suppose three sibling species of frogs have the following DNA sequences at a portion of a gene: Species 1: AGTCTAGATCGCGGTCG Species 2: AGTCGATCGCGGACG Species 3: TGTCTAGATCACGGTCG Recall that the observed number of mutations can differ from the total number of actual substitutions that occurred in pairwise sequence comparisons.If we assume that a gap of any length is equivalent to three nucleotide substitutions, how many substitutions have occurred between Species 1 and Species 2?

Genome sizes vary tremendously among organisms.Size does not directly correlate with complexity, as organisms that have similar complexities can differ by as much as 40 times.Yet, these same organisms may have similar numbers of genes, with noncoding DNA making up the tremendous difference in genome sizes.One hypothesis is that the proportion of coding to noncoding DNA in the genome of a species is related to the sizes of the populations typical of the species.Explain how the coding-to-noncoding DNA ratios in species with different typical population sizes might be related to the relative importance of natural selection and genetic drift in the evolution of the species.

Suppose that under the conditions of an experiment, a particular virus has an expected substitution rate of 1 per 2,000 nucleotides per generation and a genome size of 10,000 nucleotides.The virus has one generation per hour.We would expect _______ substitutions between 9:00 am on Monday and 1:00 pm on Friday of the same week.

Chorion genes are involved in making the eggshells of many insect species.In some species, as multiple copies of these chorion genes evolved within the same species, the similarity of the copies was maintained.This phenomenon is known as _______ evolution.

A researcher studies the evolutionary relationships between influenza viruses by comparing the genomic sequences of the viruses found in pigs, ducks, and humans in a given year.When evaluating the viruses that had infected these hosts the previous year, she identifies a cross-species transfer from humans to pigs.This information supports the hypothesis that cross-species transfer leads to more severe disease if during the previous year

Refer to the figure. Which pair of genes contains paralogs?

Suppose that under the conditions of an experiment, a particular virus has an expected substitution rate of 1 per 2,000 nucleotides per generation and a genome size of 10,000 nucleotides.The virus has one generation per hour.Suppose you wanted to have populations of this virus to acquire approximately 100 substitutions.How long would you let the experiment run?

Suppose the size of a population of frogs is 600.According to genetic drift theory, the probability that a newly arisen neutral mutation will become fixed in this population is 1 in _______.

Below are sequences of part of a gene taken from three species of plants. Plant A: AGATCTACGCGCAGTTTC Plant B: AGATTGGCGCAGTATC Plant C: AGATTAGGCGCAGTTTC Align the sequences.If each added gap required to align the sequences represents two nucleotide differences, how many differences are between species A and species B?

A team of biologists is examining the gene tree of a gene family of early embryonic development genes.They should focus on comparing _______ when mapping changes in function due to gene duplication.

Genomes consist of

A DNA substitution does not change the amino acid sequence of the protein.This change is thus a _______ substitution.

To determine the rates at which organisms lose DNA, researchers have used _______ that have LTRs.

A gene family has been accumulating nucleotide substitutions at a rate of 0.15 per million years.On average, there have been 30 substitutions between the common ancestor of this gene family and each of the various living forms of this gene.Based on these numbers, this gene family likely originated _______ million years ago.

What is the primary function of the products of the globin genes?

Mutations in the third position of codons are the least likely to affect the amino acid sequence.Mutations in the second position are most likely to change the amino acid sequence, whereas first-position mutations are intermediate.Based on what you know about molecular evolution, predict the relative rates of evolution for first-, second-, and third-position codon nucleotides, from least likely to most likely.