genetics problems ahh

Genetics as it applies to evolution, molecular biology, and medical aspects.

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biohelp22
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genetics problems ahh

Post by biohelp22 » Sun Apr 23, 2006 4:41 pm

1. Genes M and N are located on different chromosomes and the probablity of their undergoing crossing over is quite low. if the probability of allele M segregating into a gamete is 1/6 and the probability of allele N segregating into a gamete is 1/4 then the probability that both of them will segregate into the same gamete is

1/12
1/4
5/12
3/4
1

math hurts my brain but i tried it and got 1 ~.~

another one stumping me is

two individuals both of whom are carriers for cystic fibrosis ( a recessively inherited disorder) produce 3 children together , and none of these children has cf . what is the probability that the couples 4th child will beborn with cf?

0%
25%
50%
75%
100%

id say 50%???

risingstar5
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Post by risingstar5 » Sun Apr 23, 2006 5:33 pm

yeah the second one is 50%....well at least thats what i got too
Never let the odds keep you from pursuing what you know in your heart you were meant to do. <3

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MrMistery
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Post by MrMistery » Mon Apr 24, 2006 6:24 pm

1. I really don't understand the issue in debate. The probability of a gene segregating into one gamete or the other is 1/2. ALWAYS

2. A carrier for cystic fibrosis is always heterozygous(Cc). So when you cross Cc with Cc you will get:
CC 25%
Cc 50%
cc 25% - has the desease
Therefore the answer you are looking for is still 25%, regardless of the fact that the forst 3 turned out to be healthy. Meiosis can't remember how it got it last time. It's like flipping a coin 4 times. Coins can't remember what side the fell on before.
"As a biologist, I firmly believe that when you're dead, you're dead. Except for what you live behind in history. That's the only afterlife" - J. Craig Venter

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