Question

The clinic analyzes a family's genetic test results showing different types of mutations in the same gene. One mutation is silent, one is missense, and one is nonsense. The genetic counselor must explain why these mutations have different effects on health. What explains these different outcomes?
Question 5 options:

All mutations in the same gene automatically produce identical effects on protein function

The location of mutations in genes doesn't affect how they impact protein structure and function

The genetic code's redundancy means some changes don't alter amino acids, while others change protein structure or length

Silent mutations are not real mutations because they don't involve actual DNA sequence changes

Answer 1

Correct answer: The genetic code's redundancy means some changes don't alter amino acids, while others change protein structure or length.

Explanation: Because the genetic code is degenerate, a nucleotide substitution can be synonymous (silent) — different codon but same amino acid — so protein unchanged. A missense mutation changes a codon to one that encodes a different amino acid, which can alter protein structure or function. A nonsense mutation converts a codon to a stop codon, producing a truncated (usually nonfunctional) protein. The other statements are false.