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Samantha asked in Science & MathematicsBiology · 1 decade ago

Help with some Bio homework - Genetics?

I have a few questions about some answers I've come up with for my bio homework. I'll probably be posting a few others after this as I work on them. I am not looking for you to do my homework for me, just to correct me or lead me in a better direction. I think my brain is just about to explode and I'm probably starting to complicate things WAY too much. At least that how's I feel. These are the questions and answers in question:

1. In humans hemophilia A or B is caused by an X-linked recessive gene. A woman who is a nonbleeder had a father tho was a hemophiliac. She marries a nonbleeder, and they plan to have children. Calculate the probability of hemophilia in the female and male offspring.

I figured this:

Females: none

Males: 1/2

And I got to that conclusion by assuming because the father is normal and the mother is a carrier, the gene is recessive and therefore the girls cannot be affected (one X from dad is normal and dominant, so they cannot have hemophilia even if they receive the gene from their mother). The boys I got 1/2 for because there's a 50:50 chance they'd receive the gene from their mother. Am I correct or at least on the right track?

2. In humans, red-green color blindness is recessive and X-linked, while albinism is recessive and autosomal. What types of children can be produced as the result of marriages between two homozygous parents, a normal-visioned albino woman and a color-blind, normally pigmented man?

My answer:

The children can only be normal visioned and only the females will normally pigmented, while the males will be albino.

My thought process was only the girls will get an X from their dad who is color-blind, but their mom will give them normal-vision, and because that's dominant, all children will have normal vision. For albinism, the girls will receive the normal pigmented dominant gene from their father, so they will not be albino. The boys will only receive the albino X from mom, so they will all be albino. Am I at least close?

Ok, that's all I have for now. I'll post others in a new question as I go along and answer more I may get stuck on.

Update:

Ah! Zim you're totally right. I completely understand. I had that answer intially, but when I went to type it here, I redid it and acted as if it were sex-linked. I'm starting to lose it...

But thank you!

2 Answers

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  • 1 decade ago
    Favorite Answer

    You're on track for the first portion. However the albinism is autosomal and not sex linked. So the boys and girls will both receive the same set of genes. So the answer is no matter what you will be having normal vision and normal pigment.

    If you need more of an explanation let me know, but just look at it again and remember that autosomal is different than sex linked.

  • ?
    Lv 4
    5 years ago

    Your responses look properly. the finest ingredient is, not between the ideas are terrific suited for volume a million. the respond would desire to be: xCxc and xc Y (men don't have 2 alleles for intercourse-linked genes)

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