genetics calculation questions

[doc29]

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how do you guys study for genetics calculation qs? a friend of mine took it yest and he got 3 or 4 calculation stuff about gene frequency/allele.
i am really bad at gen calculation qs(got all of them wrong on UW🙁)

 

[PokerDoc]

how do you guys study for genetics calculation qs? a friend of mine took it yest and he got 3 or 4 calculation stuff about gene frequency/allele.
i am really bad at gen calculation qs(got all of them wrong on UW🙁)

keep doing them again until you get them right and do the math on paper so you can show your work!

 

[newyorker2008]

I got a handful of those questions too. You also need to know that gene frequency equation, i had 2 questions that were answerable if you had that equation memorized.

 

[doc29]

I got a handful of those questions too. You also need to know that gene frequency equation, i had 2 questions that were answerable if you had that equation memorized.

is there any review books or websites that i should read? im really weak in genetics...undergrad genetics class was horrible.

 

[PokerDoc]

the only equations you need to know are already in FA

 

[PokerDoc]

try starting here..

the two most important equations are

1) p + q = 1

2) p^2 + 2pq + q^2 = 1

p^2 is the same thing as AA

2 pq = Aa

and q^2 = aa


with that you can work your way around any of these questions

example: they tell you that 2% of the population is homozygous recessive for red hair and they want to know how many carriers there are in the population

which of those numbers is the homozygous recessive population?

its q^2 right? so q^2 = .02 ---> q ~ .14

so now p = 1 - .14 = .86

so to find the heterozygote carrier population (2pq) just plug in your numbers (2)(.86)(.14) = .24


24% of the population are heterozygote carriers of the red head curse

 

[PokerDoc]

here's another way they can get you:

If you have two parents who are heterozygote carriers for an AR mutation and they give birth to a healthy child, what is the probability that child is homozygous normal?


the answer is 33%

make sure you know why. or post if you need elaboration.

 

[doc29]

here's another way they can get you:

If you have two parents who are heterozygote carriers for an AR mutation and they give birth to a healthy child, what is the probability that child is homozygous normal?


the answer is 33%

make sure you know why. or post if you need elaboration.

thanks a lot pokerdoc, that helps alot...what about when they ask u allele, gene frequency in the q? my problem is i dont know when to use q or q^2?

 

[PokerDoc]

thanks a lot pokerdoc, that helps alot...what about when they ask u allele, gene frequency in the q? my problem is i dont know when to use q or q^2?

q is allele frequency

q^2 is homozygous recessive frequency (so someone with qq genotype)

 

[Vikingwizardguy]

here's another way they can get you:

If you have two parents who are heterozygote carriers for an AR mutation and they give birth to a healthy child, what is the probability that child is homozygous normal?


the answer is 33%

make sure you know why. or post if you need elaboration.

they LOVE this question. So many times I'd get it and be like "duh 25% idiots". Then i'd get it wrong and flip out. I will elaborate since it's such a dumb little thing, no one should get it wrong.

Aa x Aa

AA, Aa, Aa, aa would be the possible offspring. The child is normal so you automatically ignore the aa. So now you make your percentage from AA, Aa, and Aa. Which means that the chance of the kid being homozygous is one out of three. This also means that if they asked what the odds of being hetero is, it's 2/3 or 67%.