Question

When two genes from two different people are sequenced and aligned, it is discovered that there are multiple sequence differences in the coding segment DNA level. However, when the proteins formed by the genes have their amino acids sequenced, there is no difference observed between the two. What is the most likely explanation for this observation?
a. The mutations are repaired at the mRNA level after transcription has occurred, but before translation.
b. RNA processing removes the different segments from the mRNA molecules of each person prior to translation.
c. The mutations lie at locations where they don't affect protein sequence due to degeneracy of the genetic code.
d. Mutations at the DNA level are not reflected in proteins produced.
e. The mutations are corrected at the protein level after translation has occurred.

Answer 1

Answer:

The mutations lie at locations where they don't affect protein sequence due to degeneracy of the genetic code.

Explanation:

Genetic code is the set of the triplet codons each of which code for a specific amino acid. The nucleotide sequence of mRNA is read in the form of triplets during the process of protein synthesis and the respective amino acid is added to the growing polypeptide chain. The genetic code is degenerate. This means that more than one triplet code specifies one amino acid and some amino acids are encoded by more than one codon.

For instance, genetic codes CUU, CUC, CUA, CUG specify amino acid "leucine". Therefore, any change in the DNA sequence that replaces one code for the leucine with another would not affect the amino acid composition of the protein. This would result in the synthesis of proteins with the same amino acid sequence from both the wild type and mutated genes.