Question

1. a frameshift mutation involves the addition or a deletion of a base in the nitrogen base sequence. given the following mrna codon sequence: aug uau gag aau uaa a) what would happen if the g at the end of the aug codon were deleted? b) what would happen if an additional base were inserted between the first and second codons?

Explanation:

Part (a)

1. Original mRNA codons: AUG, UAU, GAG, AAU, UAA.
2. Deleting G from end of AUG: New first codon is AU (incomplete), then next codons shift. The reading frame (grouping of 3 bases) is disrupted. All subsequent codons will be misread (frameshift mutation). The start codon (AUG) is altered, and the amino acid sequence from the start will be completely changed, likely leading to a non - functional protein or premature stop (if a stop codon is formed incorrectly).

1. Inserting a base between first (AUG) and second (UAU) codons.
2. This insertion disrupts the normal reading frame (since codons are read in groups of 3). All codons after the insertion point will be shifted by one base, so their sequence (and thus the amino acids they code for) will be misread. This is a frameshift mutation, and the translated protein will have a different (and usually non - functional) amino acid sequence from the point of insertion onwards.

Answer:

Deleting the G from the end of AUG causes a frameshift mutation. The reading frame of the mRNA codon sequence is disrupted. The first codon becomes incomplete (AU), and all subsequent codons are misread. This will lead to a completely different (and likely non - functional) amino acid sequence being translated, or a premature stop codon may be encountered, resulting in a truncated protein.

Part (b)