Exam 23: Evolution of Genes and Genomes

Two species of rodents that diverged 15 million years ago have accumulated an estimated 20 nucleotide differences in a gene.Both of these rodents have one generation per year.Suppose sequence analysis of offspring and parents shows that the actual total mutation rate is 1.5 per million generations.Given this information and assuming that all mutations are either deleterious or neutral, approximately _______ of mutations are neutral.

Which is the best representation of a nucleotide substitution?

After obtaining DNA sequences from a variety of species, the most logical next step in a molecular evolutionary study is to

The human and chimpanzee sequences for a particular DNA segment are being aligned.Both happen to be the same length, but you know that there is a three-nucleotide insertion in the chimpanzee sequence, relative to the human sequence.The most likely explanation is that there was a

Consider a hypothetical enzyme-coding gene and sequences of the gene from several species of rodents.The figure shows the rates of nonsynonymous and synonymous substitutions for each of four regions of the gene. Which region appears to be under positive selection?

A gene family has been accumulating nucleotide substitutions at a rate of 0.25 per million years.On average, there have been 80 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.

Neutral substitutions accumulate between lineages primarily via

Refer to the table. We can infer that the salamander data are consistent with the hypothesis that

Which genetic event is most like lateral gene transfer in its effects?

Most emerging diseases are caused by

Refer to the figure. Which statement about the figure is false?

A gene involved in immunity duplicates within an organism, and these duplicate genes begin to diverge in their function.These different genes are considered

Two species of beetles carry a single copy of a gene that codes for an enzyme.This gene has started to diverge.The copies of this gene found in the two species of beetles are

Concerted evolution can occur through either unequal crossing over or _______.

Which statement about ribosomal RNA (rRNA) genes is false?

The most likely way for proteins to acquire new functions is via

Which statement about genome evolution is true?

Which ranking of organisms is correct in terms of the proportion of coding DNA to noncoding DNA in their genomes, from smallest proportion to largest proportion?

The table shows the amino acid sequences for an eight-residue section of a small protein for five different species (1-5). Complete the similarity matrix below using these sequences.

In a hypothetical experiment, researchers sequence a gene from a colony of bacteria at various times in the history of the colony.In the common ancestor, the nucleotide at site 998 is A.After 1,500 generations, it changes to G.After 5,000 generations, it changes back to A.We can infer that a total of _______ substitution(s) have occurred.Without knowledge of the sample taken at 1,500 generations, we would have inferred that _______ substitution(s) had occurred.