Question

Use the data below to answer the questions at the bottom.

M: (Vial 0, #47) Red,Wild type

F: (Vial 0, #100) Red,Curly

Eye Color	Wing Shape	F	M	Total
Red	Curly	0	79	79
Red	Wild type	81	0	81
Peach	Curly	0	0	0
Peach	Wild type	0	0	0

M: (Vial 0, #1) Peach,Curly

F: (Vial 0, #15) Red,Curly

Eye Color	Wing Shape	F	M	Total
Red	Curly	0	0	0
Red	Wild type	0	0	0
Peach	Curly	156	145	301
Peach	Wild type	0	0	0

M: (Vial 8, #1804) Red,Curly

F: (Vial 0, #5) Peach,Wild type

Eye Color	Wing Shape	F	M	Total
Red	Curly	30	29	59
Red	Wild type	31	33	64
Peach	Curly	32	32	64
Peach	Wild type	28	27	55

M: (Vial 9, #2219) Peach,Curly

F: (Vial 9, #2109) Peach,Curly

Eye Color	Wing Shape	F	M	Total
Red	Curly	34	41	65
Red	Wild type	0	0	0
Peach	Curly	80	80	160
Peach	Wild type	0	0	0

1. Which traits are dominant? (2pt)

2. Are these two genes inherited in the same way? Explain your answer. Indicate the mode of inheritance for each gene in your explanation. (2pt)

Answer 1

- Which traits are dominant?

About the curly-wildtype trait, look at the crosses when both parents are curly, they can only produce curly offspring. On the other hand, when the parents are wildtype they are able to produce both curly and wildtype offspring. This means Wildtype is dominant over the recessive curly trait.

In the same manner, addressing the red-peach trait, look at the crosses when both parents are red, they can only produce red offspring, but when both parents are peach they can produce both red and peach offspring. That means Peach is dominant over the recessive red.

- Are these two genes inherited in the same way? Explain your answer. Indicate the mode of inheritance for each gene in your explanation.

For this let's analyze the frequencies but for each trait independently.

+ Wildtype-curly

This treait seems to have a different inheritance mechanism between males and females, as we can see a different result in crossing number one. Let's analyze such crossing with punnet squares for both scenarios (X-linked, and autosomal):

X-linked:

Male: WY

Female: cc

	W	Y
c	Wc	cY

If the trait is X linked, then we would obtain half offspring being wildtype female and the other half being curly male.

Autosomal:

Male: Either WW or Wc

Female: cc

	W
c	Wc

In this case we have both females and males that are only wildtype.

	W	c
c	Wc	cc

In this case we have both females and males as either curly or wildtype.

Both autosomal scenarios cannot be seen in reality, while the X-linked scenario fits reality completely. The trait Wildtype-curly is X-linked.

+ Peach-red

This threat shows a regular and expected frequency distribution in the offspring for a regular autosomal trait. Let's make a punnet square with the third crossing to confirm it:

Male: rr

Female: Pr

	P	r
r	Pr	rr

We expect half and half (Peach and red), that's just what we found in our real data.

Conclusion: They are not inherited in the same way. The trait Wildtype-curly is X-linked and the trait Peach-red is autosomal.