Question

Explain the purpose of a molecular clock and the properties that a section of protein must have to be used in this way.

Answer 1

In the evolutionary sense, a molecular clock refers either to homologous proteins in different organisms, in which case divergence between the genetic and protein sequences is used to determine how long ago the organisms diverged. In the molecular sense, a molecular clock refers to a feedback loop or gene regulatory network in the cellular circuitry which keeps track of temporal patterns. Think of the sleep-wake cycle or, longer term, hibernation patterns on a seasonal basis.