Answer
Comparative biochemistry is based on the fact that the same types of molecules are found in all living things. Similar molecules and chemicals of similar structure found in different animal groups signal the possibility of evolutionary relationships.
Work Step by Step
Studies of DNA sequences and enzymes and other proteins have been very instructive in the tracing of evolutionary similarities and lineages; for example, the amino acid sequences of cytochrome C in humans and monkeys are very similar --differing in only a couple amino acids. This indicates fairly close evolutionary relationships.
Other examples of evolutionary biochemical similarities are hemoglobin amino acid sequences in hemoglobin of humans, gorillas, and chimpanzees, as well as the distribution of the enzyme trypsin among animals.
