Destroyer #228 - Help?

Discussion in 'DAT Discussions' started by STACM, Jun 21, 2008.

1. STACM 7+ Year Member

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In BIO question #228 of destroyer it says "if a male and female are both carriers of the gene, what is the probability that they have a diseased child?", but in the answer they take into account a 1/50 (2%) chance each parent carries the gene. So how can this be...in the question is says each parent IS a carrier (100% chance the parent carries the gene), but in the answer they say there is a 2% chance a parent is a carrier.

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anyone??

3. Dotoday 7+ Year Member

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Let me look at the question a little more. I`ll get back to you. Sounds like some info is missing.

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cool thanks!

5. Dotoday 7+ Year Member

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Hi, sorry to take so long to get back to you, I was not able to get on the internet.
OK, so thge questions says that the parents are 1/50 people who carry the recessive mutation, but they are only carriers , not homozygous. Therefore 1/50 people puts them at 0.02% of people that carry the mutation. You are right if both parents are carriers then they each have 50% of transmitting that information to their children and a child has 25% chance of inheriting the same mutant allele from both parents. However, you must consider the fact that each parent is 1/50 people who has the allele and therefore each parent has 0.02% chance of carrying the allele in a first place. So, what you do is you take 0.02 *0.02 (from each parent)*0.25 (chance that a child inherits mutant allele from both parents) = 0.01% chance that in withing the population the child has 0.01% chance of being a homozugous mutant. This includes the criteria that the child has both parents which have 0.02% chance each of carrying the mutant allele.
The answer is right, just the wording may be a bit confusing.
Hope this helps.

6. krnstylenow

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i dont understand this question as well.

when i first did it, i thought oh. 25% chance to be recessive homozygous, then 2% chance to be actualy sick so I thought it was 0.5% but then the answer was not there!!!

I think it is a really poorly worded question. I for sure thought it said, given the person is homozygous recessive, the probability of actually being sick is 2%.

7. klutzy1987 StudyingSucks Letsgo Mets 5+ Year Member

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The problem is it tells you that both parents are carriers so therfore why should you have to even care bout what the probability of them being carriers is. It tells you straight out that they are carriers. The answer should just be .5%

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8. NuckingFutz 7+ Year Member

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I was confused about this one too. I think that it may be an error in destroyer

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