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Mode of Inheritance when given F2 generation data

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

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Mode of Inheritance when given F2 generation data

Postby linuxux » Tue Jul 28, 2009 10:51 am

1. The problem statement, all variables and given/known data

I am supposed to hypothesize the mode of inheritance of genes when given the F2 data--the F2 numbers of a cross between two, true-breeding strains in the P generation. also, i am to indicate the expected genotypic and phenotypic ratios, and analyze the hypothesis--each trait separately in males and females--using the chi-square. The gene alleles can be either or recessive, and autosomal or x-linked.

F2 Data:
wild type, males 62
wild type, females 108
orange eyes, males 19
orange eyes, females 30
black body, males 53
black body, orange eyes, males 17

2. Relevant equations

none.

3. The attempt at a solution

There are two things that confuse me about the question. 1] How is it that we can stipulate what we expect specifically in the males and females of a population, and not rather just in the population itself? Presumably, since I am going to need to use the chi-square and analyze males and females separately, then i have to have an expected number of males and females. this i what i don't get, how can we have an expected number of males or females?

I can see a solution to this question by using the total number of females or males, and from the hypothesized mode of inheritance being able to come up with expected numbers, but this leads to my next point of contention...

2] Why is it that there are no females with black body, orange eyes genotype?
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Postby Darby » Tue Jul 28, 2009 8:16 pm

When genders are specified and some numbers are confusing, start considering sex-linked traits.
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Postby MrMistery » Wed Aug 05, 2009 1:29 am

well if your hypothesis that the thing is autosomal were true, then you would expect equal numbers for males and females in pretty much everything.

PS: Chi squared sucks. I always hated it...
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