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 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 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 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

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

Answer 1

A substitution mutation is a change in the DNA sequence where one base is replaced by another.

Let's compare each of the proposed sequences to the original sequence:

Original 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
```

Now let's evaluate the options:

1. **C G T T A C T G C A A T**
- The sequence is identical to the original, no mutation.

2. **C G T G A C T G C A A T**
- There is a substitution where the second base in the first row changes from T to G.

3. **C G T C T A C T G C A A T**
- There is a substitution where the third base in the first row changes from T to C.

4. **C G T A C T G C A A T**
- There is a substitution where the second to last base in the first row changes from T to A.

Among these, the sequences that show a substitution mutation are options 2, 3, and 4. However, since the question asks which sequence shows a substitution mutation and provides options, the first sequence that displays a clear substitution from the original sequence is:

- **C G T G A C T G C A A T** (2nd option).

So the correct response is the second option.