Question

A codon in a mutant allele of a gene is GGA while the same codon in the wild type is AGA. What type of mutation is this? A genetic code table is recommended for this problem.
A) missense

B) silent

C) nonsense

Answer 1

Answer: The correct answer is missense mutation

Explanation:

In missense mutation, the protein formed is not useful (non-functional) due to changes in its base sequence as observed in the mutant allele described.

Since, wild type Codon is AGA, Mutant allele codons of GGA signifies a "miss of sense" in the gene, as the 1st base had been change from Adenine to Guanine.

Answer 2

Answer: A) Missense

Explanation: In missense mutation, there is a substitution or replacement of one or more base pairs in the nucleotide sequence of the messenger RNA. In this case, guanine replacement adenine which leads to the synthesis of a polypeptide with a garbled amino acid sequence or a nonfunctional polypeptide. In the genetic code table, GGA codes for glycine while AGA codes for arginine.

See the attached genetic code table containing the 64 codons and the amino acids they code for, for better understanding