Question

A DNA segment has base order AGC TTA TCG. Which copy exhibits a frameshift mutation through deletion?

(1 por

AGC TCG

AGC TTA TAG

TTA TCG

AGC TTT CG

Answer 1

A frameshift mutation occurs when nucleotides are added or deleted from the DNA sequence in a number that is not a multiple of three, which causes the reading frame of the genetic code to shift.

The original DNA segment is: **AGC TTA TCG**

Let's analyze the provided options for deletions:

1. **AGC TCG** - This sequence appears to be missing one nucleotide (the second "T" from "TTA"). This deletion causes a frameshift since it changes the reading frame for subsequent codons.
2. **AGC TTA TAG** - This sequence has not undergone a frameshift mutation through deletion; it simply replaces "TCG" with "TAG," which is a substitution.
3. **TTA TCG** - This sequence is missing the first "AGC," which also results in a frameshift, but it is a deletion of three bases. This could potentially restore the reading frame if it were in multiples of three.
4. **AGC TTT CG** - This sequence has undergone a change by substituting the second "A" with "T" and deleting one "CG," which can result in a frameshift, but it can be considered a substitution and a deletion simultaneously.

Given these options, the one that clearly shows a frameshift mutation through deletion is **AGC TCG**.