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 #3
Offspring #3

Offspring #4
Offspring #4

Offspring #1
Offspring #1

Offspring #2

Answer 1

To identify which offspring has a substitution mutation compared to the parent’s DNA sequence, we will compare each offspring’s sequence to the parent's sequence and look for any differences.

Parent's DNA sequence:

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

Offspring #1 DNA sequence:

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

Difference at position 4: C (parent) vs T (offspring #1)

Offspring #2 DNA sequence:

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

Difference at position 4: C (parent) vs C (offspring #2)

Offspring #3 DNA sequence:

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

Difference at position 10: T (parent) vs G (offspring #3)

Offspring #4 DNA sequence:

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

No differences from the parent’s sequence

From the comparison, we see:

• Offspring #1 has a substitution mutation (C to T at position 4).
• Offspring #2 has no substitution.
• Offspring #3 has a substitution mutation (T to G at position 10).
• Offspring #4 has no substitution.

Final answer: Offspring #1 (substitution mutation at position 4) and Offspring #3 (substitution mutation at position 10) both have mutations. However, the question can only choose one response.

Since it asks for a substitution, the best response would be:

Offspring #1