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
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
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Answers

There are no human answers yet.
Answered by GPT-4o mini
A substitution mutation occurs when one base in a DNA sequence is replaced with another base. Let's analyze the provided sequences:

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

2. **Proposed Mutated Sequences:**

**First option (no mutation):**
- Strand 1: C G T T A C T G C A A T
- Strand 2: G C A A T G A C G T T A

(This is identical to the original sequence; no mutation)

**Second option (substitution mutation):**
- Strand 1: C G T A C T G C A A T
- Strand 2: G C A T G A C G T T A

(In strand 1, T is replaced with A; this indicates a substitution mutation)

**Third option (substitution mutation):**
- Strand 1: C G T G A C T G C A A T
- Strand 2: G C A C T G A C G T T A

(In strand 1, T is replaced with G and in strand 2 A is replaced with C; this indicates a substitution mutation)

**Fourth option (substitution mutation):**
- Strand 1: C G T C T A C T G C A A T
- Strand 2: G C A G A T G A C G T T A

(In strand 1, T is replaced with C and in strand 2 A is replaced with G; this indicates a substitution mutation)

Thus, options 2, 3, and 4 all show substitution mutations, but based on your question format, you want to identify which shows a substitution mutation.

The second option is the clearest example, as it shows a single point substitution:

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

This is where T has been replaced by A in the first strand.

Therefore, the sequence showing a substitution mutation is the **second option**.

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