Review: Brown-Eyed Man & Blue-Eyed Son - Genotypes Explained

[f4d_girl]

Hi... I just completed this assignment but I'm not sure if i did it correctly or not.. can someone review my assignment?


9. Hand- in question: A brown-eyed man whose father was brown-eyed and whose mother was blue-eyed married a woman whose father and mother were both brown-eyed. The couple has a blue-eyed son. For which of the individuals mentioned can you be sure of the genotypes? What are their genotypes? What genotypes are possible for the others?

1 = brown eye man
2 = his father
3 = his mother
4= his wife
5= wife’s father
6 = wife’s mother
7 = brown eyed man’s son

1 = Bb
2 = B? / he can be Bb or BB
3 = bb
4 = b? / she can be bb or Bb
5 = B? / he can be Bb or BB
6 = B?/ she can be Bb or BB
7 = bb

However, one should note that wife’s father and mother, both cannot be BB because the son is blue-eyed meaning that the wife is blue-eyed.

 

[Moonbear]

Everything is fine until your last sentence. As you got correct in #4, the wife has one allele for blue eyes, but could be either homozygous or heterozygous, so you cannot know if she is blue-eyed or brown-eyed.

 

[Ouabache]

Yes i concur, it looks good up to your last line. But you already stated correctly in #4 that "his wife" is either bb or Bb. You also already know that Bb is brown eyes (as in #1) and bb is blue eyes (as in #7). So I suspect your last sentence was an oversight.

Although you solution does summarize the information needed to answer your questions, I suspect you are not going to hand in your answer in this form. Often teachers would like to see each question addressed individually.

For which of the individuals mentioned can you be sure of the genotypes?

What are their genotypes?

What genotypes are possible for the others?