Question

Question 3
A)
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)
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 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 A C T G C A A T
G C A T G A C G T T A

Answer 1

A substitution mutation occurs when one nucleotide is replaced with another in a DNA sequence.

Let's start with the original DNA sequence provided:

**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, we will look at each of the options to identify the substitution mutation:

1. **C G T C T A C T G C A A T**
This first line has "T" changed to "C" (C G T C T A C T) (substitution occurred). Second line is also mutated.
**(Substitution mutation)**

2. **G C A G A T G A C G T T A**
This first line has "A" changed to "G" (G C A G A T...) (substitution occurred), second line is also mutated.
**(Substitution mutation)**

3. **C G T G A C T G C A A T**
This first line has "T" changed to "G" (C G T G A...) (substitution occurred), second line is also mutated.
**(Substitution mutation)**

4. **G C A C T G A C G T T A**
This first line has "A" changed to "C". (G C A C T ...) (substitution occurred), second line is also mutated.
**(Substitution mutation)**

5. **C G T T A C T G C A A T**
This option is identical to the original sequence - no mutations observed.
**(No mutation)**

6. **C G T A C T G C A A T**
This first line has "T" changed to "A" (C G T A C T ...) (substitution occurred). Second line is the original one.
**(Substitution mutation)**

7. **G C A T G A C G T T A**
This first line has "A" changed to "T" (G C A T ...) (substitution occurred). Second line is the original one.
**(Substitution mutation)**

Thus, all options except the last option show a substitution mutation.

If you need one clear example of substitution among them, you can select either:
- **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 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 A**

These all show a substitution mutation within the presented sequences.