Question
A DNA segment has base order TCG TAT AAC. Which copy exhibits an insertion mutation
without a frameshift? (1 point)
TCC TAT AAC
TCG CCG TAT AAC
TCG TAT GAAC
TCG TAT AC
without a frameshift? (1 point)
TCC TAT AAC
TCG CCG TAT AAC
TCG TAT GAAC
TCG TAT AC
Answers
GPT-4o mini
To understand which copy exhibits an insertion mutation without a frameshift, we need to first look at the original DNA segment and see how the mutations compare to it. The original sequence is:
**TCG TAT AAC**
1. **TCC TAT AAC** - This shows a point mutation (the first base changed from G to C) but no insertion.
2. **TCG CCG TAT AAC** - This shows an insertion of "CC" after "TCG", resulting in a frameshift.
3. **TCG TAT GAAC** - This shows an insertion of "G" after "TAT", which does not cause a frameshift since the number of bases inserted is equal to one base in the same reading frame. Hence, this is a valid insertion mutation without a frameshift.
4. **TCG TAT AC** - This shows a deletion of "A" without any insertion.
Thus, the **correct answer** is:
**TCG TAT GAAC** (this exhibits an insertion mutation without a frameshift).
**TCG TAT AAC**
1. **TCC TAT AAC** - This shows a point mutation (the first base changed from G to C) but no insertion.
2. **TCG CCG TAT AAC** - This shows an insertion of "CC" after "TCG", resulting in a frameshift.
3. **TCG TAT GAAC** - This shows an insertion of "G" after "TAT", which does not cause a frameshift since the number of bases inserted is equal to one base in the same reading frame. Hence, this is a valid insertion mutation without a frameshift.
4. **TCG TAT AC** - This shows a deletion of "A" without any insertion.
Thus, the **correct answer** is:
**TCG TAT GAAC** (this exhibits an insertion mutation without a frameshift).