The Most Important Feature That Permits a Gene to Act

Question

The most important feature that permits a gene to act as a molecular clock is
A) having a large number of base pairs.
B) having a larger proportion of exonic DNA than of intronic DNA.
C) having a reliable average rate of mutation.
D) its recent origin by a gene-duplication event.
E) its being acted upon by natural selection.

Accepted Answer

The most important feature that permits a gene to act as a molecular clock is having a reliable average rate of mutation. This rate allows scientists to estimate the time elapsed between divergent species or populations by comparing the differences in the nucleotide sequence of the gene. If the rate of mutation is not reliable, it would be difficult to use the gene as a clock. Having a large number of base pairs or a larger proportion of exonic DNA than intronic DNA, recent origin by gene-duplication or being acted upon by natural selection are not essential for a gene to act as a molecular clock.