Different genes and different parts of the same gene evolve at different rates. Those parts of genes that have the least effect on function tend to evolve at the highest rates. The idea of the molecular clock is that individual proteins and genes evolve at a constant rate and that the differences in the sequences of presentday organisms can be used to date past evolutionary events.
-In general, which types of sequences are expected to exhibit the slowest evolutionary change?

Question

Quizplus · Accepted Answer

Nonsynonymous changes in amino acid coding regions of exons are expected to exhibit the slowest evolutionary change because they alter the amino acid sequence of proteins, which can affect protein function and are thus subject to stronger purifying selection.

Different Genes and Different Parts of the Same Gene Evolve