University of California DNA vs. Amino Acid Lab Report

Evolutionary Rate and Choosing DNA vs. Amino Acid

Proteins that are used to carry out essential cellular functions, such as DNA replication or protein synthesis, tend to be highly conserved—i.e. the genes that encode them are under heavy purifying selection. Most non-silent mutations that arise in essential cell function genes tend to kill the organism prior to reproducing because they affect the amino acid sequence and thus the protein function may be compromised. If the organisms do not survive to reproduce, those mutations do not accumulate in the gene pool. Mutations that do not negatively affect the function of the protein also occur and may accumulate, but generally, evolutionary change in these types of genes is very slow since most mutations are not preserved.