Question

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) Responses CCC TAG CT CCC TAG CT CCA TAG CT CCA TAG CT CCA ATA GCT CCA ATA GCT CCA TAA CT

Answer 1

To analyze the provided DNA segment (CCC ATA GCT) and determine which response exhibits a deletion in the first codon triplet (CCC) followed by a substitution mutation, let's break this down step by step.

1. **Original DNA sequence**: CCC ATA GCT
- Codon triplets: CCC | ATA | GCT

2. **Deletion in the first codon triplet**: This means we need to remove one or more bases from "CCC". If we delete one base, we could lose any one of the "C" bases:
- Possible deletion scenarios:
- **C** removed: CC ATA GCT
- **C** removed: C C A ATA GCT
- **C** removed: CC C ATA GCT

However, the most likely deletion for simplicity would be the last **C**, resulting in "CC" instead of "CCC".

3. **Substitution mutation**: After identifying the first codon as CC, we now consider what substitution might occur next.

Now let’s look through the provided options to identify which one has these changes:

1. **CCC TAG CT** — No deletion or substitution present.
2. **CCC TAG CT** — No deletion or substitution present.
3. **CCA TAG CT** — Indicates a deletion of one "C" (leaving CC) followed by a substitution of the last "C" to "A" (CCA).
4. **CCA TAG CT** — Again indicates a deletion of one "C" and a substitution.
5. **CCA ATA GCT** — Similar deletion and substitution as above; however, it replaces the second codon.
6. **CCA ATA GCT** — Same as above, indicating a deletion and substitution on the second triplet.
7. **CCA TAA CT** — This option features a deletion and a substitution, but it’s unclear which ones exactly correlate with our initial assessment.

**Best Match**: The most appropriate answer based on the mutation pattern (deletion in the first codon and a substitution) is:

**CCA TAG CT**

This indicates the deletion of one 'C' from "CCC" to form "CC" and then substitutes the last 'C' in that triplet with an 'A' to form "CCA".