Loss of Function Mutations

are you in the general genetics class at asu??, i am too lol im looking for help with the same question

Yes!

I am trying to answer the same question. I haven't had any luck.

i can get the punnett square that shows the ratio, im thinking that the blue coloring masks the other ones but i dont quite understand how..  and i dont think i  understand the loss of function idea either. 

i'm hoping someone answers this soon, not having any luck with this question either

I am so confused I haven't even been able to figure out the punnet square. Could you give me any help? Honestly I would be so grateful for even a hint!

I'm in the same class. I'm pretty sure this question is impossible. I've been working on it for hours. I've drawn out the punnet squares, but have no idea which bugs are blue...or how to even get a blue wild-type.


For the F1 punnet square I crossed a AAbb (red) with an aaBB (white), which ended up giving me all heterozygous individuals presumed to be purple bugs. Then, I crossed two heterozygotes, AaBb and AaBb. After that, I got completely lost.

Haha I'm in this class too. This question is ridiculous.

Ohhhh my god, I've been working on this for hours but I think I've got it guys.

So the Purple and Blue colored bugs share what would be the 9 part of the 9:3:4 ratio that's in recessive epistasis so the F2 generation goes as follows:

AABB(b) AABb(p) AaBB(b) AaBb(p)

AABb(p) AAbb(w) AaBb(p) Aabb(w)

AaBB(b) AaBb(p) aaBB(r) aaBb(r)

AaBb(p) Aabb(w) aaBb(r) aabb(w)

so the p,b,r,w stand for the color

- anything with a "bb" will have the white color, there's four of them so that makes sense
- anything with an "aa" will be red, there's only three of them
- the purple color will only show up if there's a "AaBb" genotype, there's six
- and the blue color will only show up if there's a "A_BB" genotype, it wont matter if the second "a" is big or small (as long as one of them is a big A) the dominant "B's" will over power whatever the "A's" are, so there's 3 blue bugs

And I guess the loss of function comes into play where the little "b" in the AaBb (purple) genotype makes the blue coloration in the Blue wild type bug less prominent.

Let me know if this makes sense!

at the bottom of that question it asks for the dominance relationship between the wild type and the associated loss of function mutation and it's incomplete dominance because it is an intermediate between blue (wild type) and red (loss of function mutation).

Good luck on the essay part of the exam.

I've figured it out guys.

A_bb (Red)
anything with aa: Turn (White)
A_BB Wild type (Blue)
A_Bb Turn (Purple)

The reason why it is because the genotype of their F1 generation: AaBb x AaBb

do you guys know what means will-type and true-breeding? the red should be true breeding. bur A_BB is not

Stanleyblythe, so for the essay section are you saying that it is incomplete dominance that causes the purple color? Or is it due to the loss-of-function having leaky/hypomorphic mutations?

Post Merge: 9 years ago

So, for the essay section are you saying that it is incomplete dominance that causes the purple color? Or is it due to the loss-of-function having leaky/hypomorphic mutations?

Post Merge: 9 years ago

What are you saying for the essay section: "Identify the dominance relationships between the wild-type alleles and the associated loss-of-function mutations. Explain how the pathway and the dominance relationships produce the 6:3:3:4 F2 ratios"

I'm thinking that the wild-type allele, B, is dominant. However, the presence of the recessive mutation allele, b, makes the wild-type allele less efficient. This would be due to a leaky/hypomorphic type of loss of mutation. Because of this, even though the purple flowers have the dominant wild-type allele, B, the phenotypic blue color would not be as prominent.