Describe what a "molecular clock" is. How do scientists choose which kinds of genes to use? What type of mutations do they look for, and
how might a molecular clock be used to build a phylogenetic tree for
related species?

answer; /// i believe the name is ( check first good luck.hope this

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.