Question

The following question has two parts. First, answer Part A. Then, answer Part B.

Part A:

The image shows an example of a deletion mutation.

An original D-N-A strand reads C-T-G-G-A-G with the first two G's crossed out. The mutated D-N-A strand reads C-T-A-G.

When did the mutation most likely occur?

A.
before transcription

B.
during transcription

C.
during translation

D.
after translation

Multiple Choice Question
Part B:

Which best supports the choice from Part A?

A.
Deletion mutations occur during DNA replication, changing how DNA is transcribed.

B.
Deletion mutations occur after DNA replication, changing how mRNA is translated.

C.
Deletion mutations occur during protein synthesis, changing the order of polypeptides.

D.
Deletion mutations occur after protein synthesis, changing the proteins that are formed.

Answer 1

Part A: A (before transcription)

Part B: A. Deletion mutations occur when DNA is copied (DNA replication) and thus alter the DNA sequence that is later transcribed into mRNA, changing the resulting protein.