A frameshift mutation through deletion occurs when one or more nucleotides are removed from a DNA sequence, resulting in a shift in the reading frame of the codons.
Given the original DNA segment: AGC TTA TCG.
Let's analyze each response option to determine whether it exhibits a frameshift mutation through deletion:
-
AGC TTT CG:
- This sequence has deleted one nucleotide (the 'A' from ('TTA'), resulting in a frameshift.
-
AGC TCG:
- This sequence has deleted two nucleotides (the 'TTA'), resulting in a frameshift.
-
AGC TTA TAG:
- This sequence retains all original nucleotides, with the 'C' replaced by 'TAG'. This does not indicate a deletion and would actually indicate a substitution mutation.
-
TTA TCG:
- This sequence has deleted the first codon (AGC) completely, which also results in a frameshift.
From this analysis, both AGC TTT CG and AGC TCG exhibit frameshift mutations through deletions, but if we are looking for a single response that exhibits deletion strictly shortening the sequence in the original reading frame, AGC TCG is a more straightforward example of a frameshift mutation through removal.
Based on the clarification regarding frameshift through deletion, the best responses indicating this mutation would be:
- AGC TCG (deleting 'TTA').
So the correct answer is AGC TCG.
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