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

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Postby Melly1657 » Mon Mar 12, 2007 2:19 am

A female who does not carry the color blindness allel has children with a male who is color blond. What proportion of their children will be colorblind? all- 1/4-1/2-or 3/4
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Postby Melly1657 » Mon Mar 12, 2007 2:51 am

please help answer this question!
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Postby LilKim » Mon Mar 12, 2007 4:30 am

your question is missing a few details... is this an X linked, Y linked, recessive or dominant inheritance?
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Postby 2Loula » Tue Mar 13, 2007 1:10 pm

Colour Blindness is an X-linked recessive trait. If a female has normal vision, and to have colour-bind children, she would either have to be a carrier of the recessive gene, and/or be married to a colour blind male.

For example, a cross between a colour-blind male (XrY) and a normal vision woman who is a carrier (XRXr) could have four possible offspring combinations.

1. Colour-blind male(XrY) - 1/4 or 25%
2. Normal Vision Boy(XRY) - 1/4 or 25%
3. Colour-blind female(XrXr) - 1/4 or 25%
4. Normal Vision Female carrier (XRXr) - 1/4 or 25%

However, since it is a sex-linked disease carried on the X chromosome, if the female does not have the colour-blindness allele at all, there is no way any of her children will be colourblind (though any female daughters will be carriers).

I hope this helps.
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Postby loveangel » Tue Mar 13, 2007 1:36 pm

the female needs 2 allele to inherit the colorblindness or baldness, while the male only needs 1...

but if their offspring is a female, then there's a possibility that the female offspring will be a carrier..
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Postby loveangel » Tue Mar 13, 2007 1:40 pm

there's this process to find the answer, the cross pollination.
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Re: Question

Postby Revenged » Tue Mar 13, 2007 8:53 pm

Melly1657 wrote:A female who does not carry the color blindness allel has children with a male who is color blond. What proportion of their children will be colorblind? all- 1/4-1/2-or 3/4


Colour blindness is a X-linked recessive condition...

In this case the parents alleles are:

Mother : XX (not a carrier) vs. Father: XcY (sufferer of disease)

Offspring with be:

2 x Female carriers (XcX)
2 x Normal Males (XY)

So none of your answers are correct... In this case, none of the children would be colour blind...
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Postby Revenged » Tue Mar 13, 2007 8:55 pm

2Loula wrote:However, since it is a sex-linked disease carried on the X chromosome, if the female does not have the colour-blindness allele at all, there is no way any of her children will be colourblind (though any female daughters will be carriers).


Yes, exactly...
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Postby Dr.Stein » Tue Mar 13, 2007 11:48 pm

loveangel wrote:there's this process to find the answer, the cross pollination.

Pollination? :?
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