Question

A DNA segment has base order TCG TAT AAC. Which copy exhibits an insertion mutation without a frameshift?(1 point)
Responses

TCC TAT AAC
TCC TAT AAC

TCG CCG TAT AAC
TCG CCG TAT AAC

TCG TAT AC
TCG TAT AC

TCG TAT GAAC

Answer 1

To identify a copy that exhibits an insertion mutation without a frameshift, we need to understand that an insertion mutation adds one or more nucleotides into a DNA sequence but does not disrupt the overall reading frame, meaning the triplet codons remain aligned with their corresponding amino acids.

The original DNA segment is: **TCG TAT AAC**

Let's analyze the provided options:

1. **TCC TAT AAC** - This is a substitution (T to C) and does not exhibit an insertion.
2. **TCG CCG TAT AAC** - This shows an insertion of "CCG" which adds an extra codon, causing a frameshift after the insertion.
3. **TCG TAT AC** - This is a deletion (missing nucleotide), not an insertion.
4. **TCG TAT GAAC** - This shows an insertion of "GA" following "TAT". It adds 2 nucleotides but keeps the rest of the sequence aligned to triplets, thus does not cause a frameshift.

Based on the options, **TCG TAT GAAC** is exhibiting an insertion mutation without causing a frameshift since the alignment of the triplets is maintained after the insertion.