Question

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

TCG TAT GAAC
TCG TAT GAAC

TCC TAT AAC
TCC TAT AAC

TCG TAT AC
TCG TAT AC

TCG CCG TAT AAC

Answer 1

To identify a copy of the DNA segment that exhibits an insertion mutation without a frameshift, we need to understand what a frameshift is. A frameshift mutation occurs when the insertion or deletion of nucleotides changes the reading frame of the DNA sequence. This typically happens when the number of nucleotides inserted or deleted is not a multiple of three.

The original sequence is TCG TAT AAC.

Let's evaluate the options given:

1. **TCG TAT GAAC**: This sequence has inserted an 'A' between 'GA' which is a single nucleotide insertion (insertion of 'A'). Since only one nucleotide was inserted, there is no frameshift.

2. **TCC TAT AAC**: This sequence has a substitution at the first codon (changing TCG to TCC). This is not an insertion mutation.

3. **TCG TAT AC**: This sequence has a deletion (removal of 'A') and is therefore not an insertion mutation.

4. **TCG CCG TAT AAC**: This sequence has inserted 'CC', which is a two-nucleotide insertion. Since it is not a multiple of three, it would result in a frameshift mutation.

The only option that shows an insertion without causing a frameshift is:

**TCG TAT GAAC**.