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

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

To identify a substitution mutation, we need to compare the original DNA sequence with the options provided and look for a change in a single nucleotide that replaces another.

The original sequences are:

**Original Sequence 1:**
C G T T A C T G C A A T
**Original Sequence 2:**
G C A A T G A C G T T A

Now, let's review the options you provided:

1. **Option 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
(Here, G is substituted for T in sequence 1, and C is substituted for A in sequence 2.)

2. **Option 2:**
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 mutations - identical to the original)

3. **Option 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
(Identical to the original; thus, no substitutions)

4. **Option 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
(C is substituted for T in the first sequence, A is substituted for A, and thus it has substitutions)

5. **Option 5:**
C G T A C T G C A A T
G C A T G A C G T T A
(T is substituted for T in the first sequence, making it a substitution in the original sequence and A is substituted for C in the second sequence)

Based on the definitions of substitution mutations:

- **Option 4** includes a change from T to C in the first sequence, making this a substitution mutation.

So, **Option 4** shows a substitution mutation.