Genetics Question

Question

A student has widow's peak which is dominant. Both of his parents do not have widow's peaks. What are the genotypes of both his parents?

Answer 1

What's a widow peak?

Answer 2

We know widow's peak is dominant. We can use W for the widow's peak allele. If the student has it (phenotype of this characteristic), they must not have both recessive ww, so only WW, Ww, wW are possible.

I would create a family tree diagram to solve it.

Both parents don't have it, so they must be ww.

ww   ww

However, it would be impossible for the sudent to have the phenotype in this case as there are no W's from the parents genes. I would start to look at this phenotype being only carried on the X chromosome, so

mother must be: ww  since she does not have it

father could be: wW  where W is on the Y allele (would not show up)

Their offspring could then be the cross product of wW and ww: so wW is possible.

Hope this helps!

Comments

I didn't get any of it.

---

An X chromosome is what gives you your intellegence. It looks like the letter x. Females have two and males have one. There is a disease which damages one of your X chromosomes and makes you less intellegent. One in nine adult females have this disease. Scientists think this disease could be more common in females than males.