Question

Look at the DNA sequence.

C G T T A C T G C A A T
G C A A T G A C G T T A
Which sequence shows a substitution mutation?

(1 point)
Responses

C G T G A C T G C A A T
G C A C T G A C G T T AC G T G A C T G C A A T G C A C T G A C G T T A

C G T A C T G C A A T
G C A T G A C G T T AC G T A C T G C A A T G C A T G A C G T T A

C G T T A C T G C A A T
G C A A T G A C G T T AC G T T A C T G C A A T G C A A T G A C G T T A

C G T C T A C T G C A A T
G C A G A T G A C G T T AC G T C T A C T G C A A T G C A G A T G A C G T T A
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Answer 1

A substitution mutation involves a change in one or more nucleotides in the DNA sequence.

Let's analyze the options given.

1. **C G T G A C T G C A A T**
**G C A C T G A C G T T A**
(The first sequence changes from T to G at the 3rd position, and the second sequence changes from A to C at the 3rd position.)

2. **C G T A C T G C A A T**
**G C A T G A C G T T A**
(The first sequence changes from T to A at the 3rd position, and the second sequence changes from A to T at the 3rd position.)

3. **C G T T A C T G C A A T**
**G C A A T G A C G T T A**
(No changes; it's the same as the original.)

4. **C G T C T A C T G C A A T**
**G C A G A T G A C G T T A**
(The first sequence changes from T to C at the 3rd position, and the second sequence changes from A to G at the 3rd position.)

From the analysis, the sequences that reflect a substitution mutation are the first, second, and fourth options. However, the question seems to imply looking for a distinct substitution from the original sequence.

**Option 2** clearly shows a substitution at the first position of the second sequence: T to A.

Therefore, the correct answer showcasing a substitution mutation is:
**C G T A C T G C A A T
G C A T G A C G T T A**