Question

A hypothetical mRNA, AUG CGC CUA AAG AGG, codes for five amino acids. What will happen if you delete the first ‘C’? Will five amino acids still be coded for? Give reasons.

Answer 1

No. Deleting that first C causes a frameshift, and you will NOT get five amino acids; translation will stop after two.

• Original mRNA (grouped in triplets): AUG - CGC - CUA - AAG - AGG → Met - Arg - Leu - Lys - Arg (five amino acids).
• Mutated: AUG (Met) - GCC (Ala) - UAA (STOP) - AGA - GG

Reason:

The genetic code is read as non‑overlapping triplets from a fixed reading frame. A single‑nucleotide deletion shifts the frame (a frameshift mutation), changing every downstream codon and usually creating an early stop codon. Frameshift deletions, therefore, typically abolish the original amino‑acid sequence beyond the mutation.