Question

Choose all potential reasons that amino acid sequences are used to study more distantly related groups of organisms? (Think about what amino acid sequences are from a DNA/RNA perspective)

A. You want as many sequence differences as possible in closely related taxa.

B. Silent mutations in the DNA will make no difference to the amino acids.

C. The difference is that through genetic recombination, organisms can be linked together easily over short evolutionary distances, but when it comes to the more distantly related groups, amino acid sequences become more useful due to their higher likelihood to be conserved.

D. It reduces the number of changes between taxa.

E. DNA is often thought of as the genetic material that is passed along from generation to generation, and that is what we use to link organisms to their ancestors.

F. Looking at the amino acid sequences gives a functional meaning to the mutations, which DNA sequences do not provide.

Answer 1

• The difference is that through genetic recombination, organisms can be linked together easily over short evolutionary distances, but when it comes to the more distantly related groups, amino acid sequences become more useful due to their higher likelihood to be conserved - Since, protein sequence are under selective constraint for protein function and protein structure, they are conserved over much longer periods than the individual codons.
• Looking at the amino acid sequences gives a functional meaning to the mutations, which DNA sequences do not provide - Since proteins are the products of translation after transcription, the expression of the mutations that occurred in the DNA can be observed with protein sequences.