To determine which of the given replicated DNA strands contains a single substitution mutation, we need to compare each option to the original template strand.
The original template strand is: 5'-A T C G C C G A T A C T-3'
The corresponding complementary strand would be: 3'-T A G C G G C T A T G A-5'
Now, let's analyze the options for any single substitution mutation:
a. 3'-T A G C G G C T A T C A-5'
- This strand is mostly identical to the complementary strand but has a C substituted with an A in the last position.
b. 3'-T A A G C G G C T A T G A-5'
- In this strand, there is a substitution of T for G (the second position).
c. 3'-T A G C G G C T A T G A T G A-5'
- This strand is longer than the original and includes extra bases.
d. 3'-T A G G G C T A T G A-5'
- This strand has a substitution G for the original C in the second position and is also shorter than the predicted complementary strand.
Looking for a single substitution:
- a has a single substitution (C to A) compared to the correct complementary sequence.
- b has a substitution (G to A), but it affects two positions.
- c has extra bases, indicating it wouldn’t just be a substitution.
- d contains more than one substitution.
Thus, the strand that shows a single substitution mutation compared to the expected complementary strand is: a. 3'-T A G C G G C T A T C A-5'
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