A scientist is tracking the evolution of a gene in giant African snails that determines the direction of the spiral in shells. The following DNA sequence data was taken from a population of giant African snails:

Question

DNA from Snail Parent for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

T

T

A

C

G

C

A

T

A

C



DNA from Snail Offspring #1 for Corkscrew Shell Gene:

A

A

T

T

C

G

T

A

T

G

T

T

A

A

G

C

A

T

A

C



DNA from Snail Offspring #2 for Corkscrew Shell Gene:

A

A

T

C

G

T

A

T

G

T

T

A

G

C

A

T

A

C



DNA from Snail Offspring #3 for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

G

T

T

A

C

G

C

A

T

A

C

C



DNA from Snail Offspring #4 for Corkscrew Shell Gene:

A

A

T

G

C

G

T

A

T

G

T

T

A

C

G

C

A

T

A

C



Compared to the parent’s DNA sequence, identify the snail offspring that has a substitution mutation in the corkscrew shell gene.

(1 point)
Responses

Offspring #4
Offspring #4

Offspring #1
Offspring #1

Offspring #3
Offspring #3

Offspring #2

Answer 1

To identify which snail offspring has a substitution mutation compared to the parent’s DNA sequence, we should compare each offspring's DNA sequence to the parent's DNA sequence.

Parent DNA Sequence: A A T G C G T A T G T T A C G C A T A C

Offspring #1: A A T T C G T A T G T T A A G C A T A C

• Differences: Position 4 (G -> T) and Position 12 (C -> A)

Offspring #2: A A T C G T A T G T T A G C A T A C

• Differences: Position 4 (G -> C) and Position 12 (C -> G)

Offspring #3: A A T G C G T A T G G T T A C G C A T A C

• Differences: Position 9 (T -> G)

Offspring #4: A A T G C G T A T G T T A C G C A T A C

• No differences compared to parent.

Based on this analysis, the only offspring that has a single substitution mutation, where a base is replaced by another base, is Offspring #3 (from T to G at position 9).

Final Answer: Offspring #3