Question

When DNA replication occurs before meiosis, the original DNA strand CAG TGT TTA TAG is copied into complementary strand GTC ACA GGC ATC. What type of mutation has occurred?
Responses
A deletiondeletion
B insertioninsertion
C inversioninversion
D substitution

Answer 1

To determine what type of mutation has occurred, we need to compare the original DNA strand with the complementary strand produced after replication.

The original strand is:
CAG TGT TTA TAG

If we replicate this strand, the complementary bases should be as follows:
- C pairs with G
- A pairs with T
- G pairs with C
- T pairs with A
- G pairs with C
- T pairs with A
- T pairs with A
- A pairs with T
- G pairs with C

So the correct complementary strand derived from the original strand CAG TGT TTA TAG should be:
GTC ACA AAT ATC

However, the complementary strand you provided is:
GTC ACA GGC ATC

Now let's break down the differences:
1. The 6th position: In the original (T) it's represented as (G) in the copy.
2. The 7th position: In the original (T) it's represented as (G) in the copy.

The rest of the sequences match, but those bases have been changed: T has been replaced by G.

This indicates a substitution mutation, where one nucleotide in the DNA sequence is replaced with another.

Thus, the correct answer is:
**D. substitution**