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 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 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

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

Answer 1

A substitution mutation occurs when one base pair in a DNA sequence is replaced by another base pair.

Let's analyze the provided sequences to identify which one shows a substitution mutation:

1. **Original Sequence:**
- Strands:
- 1st Strand: C G T T A C T G C A A T
- 2nd Strand: G C A A T G A C G T T A

2. **Sequences Analyzed:**

- **First Option:**
- 1st Strand: C G T T A C T G C A A T
- 2nd Strand: G C A A T G A C G T T A
- No changes made; these are the original sequences.

- **Second Option:**
- 1st Strand: C G T A C T G C A A T
- 2nd Strand: G C A T G A C G T T A
- The first strand has "T" changed to "A" (substitution).

- **Third Option:**
- 1st Strand: C G T G A C T G C A A T
- 2nd Strand: G C A C T G A C G T T A
- The first strand has "T" changed to "G" (substitution).

- **Fourth Option:**
- 1st Strand: C G T C T A C T G C A A T
- 2nd Strand: G C A G A T G A C G T T A
- The first strand has "T" changed to "C" (substitution).

**Conclusion:** The sequences displaying substitution mutations are the **Second**, **Third**, and **Fourth options**. Since you ask for one option but more than one fits the criterion, the **Second Option** is clear and straightforward as it shows a substitution distinctly.

Answer: **C G T A C T G C A A T / G C A T G A C G T T A** (second option).