Question

Which of the following types of gene mutations in a protein coding gene usually have the least severe effect on the phenotype?

a) Frameshift mutations
b) Nonsense mutations
c) Missense mutations
d) Silent mutations

Answer 1

Silent mutations typically have the least severe effect on the phenotype compared to frameshift, nonsense, and missense mutations because they do not change the amino acid sequence of a protein.

Step-by-step explanation:

Among the different types of gene mutations in a protein-coding gene, silent mutations usually have the least severe effect on the phenotype.

Silent mutations do not alter the amino acid sequence of a protein because they result in a codon that encodes the same amino acid, due to the redundancy of the genetic code.

This means the protein produced is unchanged and the mutation is often undetectable without sequencing the gene.

Other types of mutations like frameshift mutations (which can be the result of insertion or deletion of a nucleotide), nonsense mutations (which create a premature stop codon and often lead to a truncated, non-functional protein), and missense mutations (which substitute one amino acid for another) generally have more significant effects on the phenotype and can result in non-functional proteins.