A DNA segment has base order CCC ATA GCT. Which copy exhibits a deletion in the first codon triplet and then a substitution mutation? (1 point)

Question

O CCA TAG CT
0 CCC TAG CT
О ССА ТАА СТ
O CCA ATA GCT

Answer 1

To determine which copy exhibits a deletion in the first codon triplet (CCC) and then a substitution mutation, let's analyze each option.

The original base order is: CCC ATA GCT.

1. Option A: CCA TAG CT

   • First codon has a deletion (C [removed] → CA), so there is a deletion here.
   • The second codon has a change from ATA to TAG (substitution mutation).

2. Option B: CCC TAG CT

   • No deletion in the first codon; it remains CCC. Additionally, no substitution has occurred in the subsequent codons.

3. Option C: CCA TAA CT

   • The first codon has a deletion (C [removed] → CA). However, this doesn't show a substitution in the second codon because it stays the same as TAA (a point mutation).

4. Option D: CCA ATA GCT

   • There is a deletion in the first codon (C [removed] → CA) but no substitution in the second codon (ATA).

After analyzing these options, Option A (CCA TAG CT) is the correct one, as it reflects a deletion in the first codon (CCC to CCA) and a substitution mutation (ATA to TAG).