(Solved) What are the chances of Mary and Mike having a sickle cell and who is a carrier?

ilovejapanmus

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11 years ago

What are the chances of Mary and Mike having a sickle cell and who is a carrier?

Inheritance: Two Trait Crosses, Incomplete Dominance, Multiple Alleles, And X-Linked Inheritance

Sickle cell anaemia is carried on a recessive allele. Normal is dominent. Mary is normal (but not a carrier).

a) What are the chances of Mary and Mike having a sickle cell child?

b) What are the chances of them having a child who is a carrier?
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For A I put:
Mary: XS Xs
Mike: Xs Y
Children: 50% chance of having a sickle cell anameia
50% chnace of being normal

Not sure if this is right and I am stuck on B.

I am not asking fr anyone to DO my homework, but it is a good wat to check my answers and help me. I am doing Bio 12 thru correspondese and appreciate the help
Shoot! I messes that up a bit! SORRY this is the correct start of the question:
Sickle anaemia is carried on a recessive allele. Normal is dominent. Mary IS a carrier for sickle cell and MIKE is normal but NOT a carrier.

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lemonsplk

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11 years ago

you didn't give any info about mike?!

may be u mean that
mary:SS and mike:SS or Ss
a)so, SS x SS
0% diseased

b)SS x Ss
50% carrier

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Lem_23

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11 years ago

Its been awhile but....

If Mary is normal and not a carrier then the genes she contributes are sickle cell free, so none of the children will have sca although, if Mike is a carrier, then the children have a 50% chance of being carriers, too. If Mike actually has sickle cell anemia, then 100% of the children will be carriers but none of them will have sca because their mother is normal.

Why?

You need the sc from both parents to exhibit the disease, otherwise, you're just a carrier. If one parent is normal, there's no way the child can be more than a carrier because, at most, only one of the parents (the other parent) will be passing on the sc gene.

If the other parent has sc, then both of that other parent's genes have sc because, if it were only one gene, that parent would be just a carrier, right? Therefore all children have a 100% chance of getting an sc gene from an affected parent but only a 50% chance of getting the sc gene from a carrier parent (they have a 50-50 chance of getting either the carrier gene or the normal gene).

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lemonsplk

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11 years ago

If Mary is a carrier, her genotype is AS (that is, she has the sickle cell trait), if Mike is normal and not a carrier, his genotype is AA. In each pregnancy, they have a 25% chance of having a child who is a carrier (with sickle cell trait , just like Mary) but none of their children will have the sickle cell disease.

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lemmona

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11 years ago

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What are the chances of Mary and Mike having a sickle cell and who is a carrier?

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