A frameshift mutation occurs when nucleotides are added or deleted from a DNA sequence. This alters the reading frame of the sequence, affecting the downstream amino acid sequence.
Looking at the original sequence: AGC TTA TCG.
-
AGC TTT CG: This is a substitution (T instead of A) rather than a deletion, so it’s not a frameshift mutation.
-
AGC TTA TAG: This is a substitution as well (TCG replaced by TAG), so it’s also not considered a frameshift mutation.
-
TTA TCG: This removes one base, but the first two bases ("AG") are deleted. This is a deletion and causes a frameshift.
-
AGC TCG: This also has a deletion where TTA is removed, leading to a frameshift.
Both options 3 and 4 can exhibit a frameshift mutation, but they interact with the sequence differently based on the positions of the deletions. However, option 3 is a direct deletion of a whole codon (not specifically from the start), while option 4 changes the last two base pairs at the end and might not represent a frameshift relative to the original structure, depending on context.
Based on this analysis, the best answer indicating a frameshift mutation through deletion is:
TTA TCG
16 answers