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

A gene can act as a molecular clock only if it has a reliable average rate of mutation. This means that the gene should accumulate mutations at a relatively constant rate over time, which can be used to estimate the divergence times between species. Genes with a larger number of base pairs or a larger proportion of exonic DNA do not necessarily have a reliable rate of mutation. Similarly, the recent origin of a gene by a gene-duplication event or its being acted upon by natural selection may affect its rate of mutation, making it unsuitable for use as a molecular clock.