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 #2
Offspring #2

Offspring #1
Offspring #1

Offspring #3
Offspring #3

Offspring #4

Answer 1

To identify which snail offspring has a substitution mutation compared to the parent's DNA sequence, we need to compare the DNA sequences of the offspring with that of the parent.

Parent DNA Sequence:

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

Offspring DNA Sequences:

• Offspring #1:

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

• Offspring #2:

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

• Offspring #3:

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

• Offspring #4:

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

Now, let's break down the differences observed:

Offspring #1:

• 4th position: Parent - G, Offspring #1 - T (mutation)

Offspring #2:

• 4th position: Parent - G, Offspring #2 - C (mutation)

Offspring #3:

• 10th position: Parent - T, Offspring #3 - G (mutation)

Offspring #4:

• No differences from the parent sequence.

From the analysis, Offspring #1 and Offspring #2 both have substitution mutations, but Offspring #3 has a mutation in the 10th position, making it distinct.

However, Offspring #1 has only one substitution (4th position) compared to the parent, and if considering single substitutions against the original sequence.

The answer based on having a clear substitution mutation compared to the parent’s sequence is:

Offspring #1