Question

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

Moderators: honeev, Leonid, amiradm, BioTeam

Post Reply
Melly1657
Garter
Garter
Posts: 2
Joined: Mon Mar 12, 2007 2:13 am

Question

Post by 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

Melly1657
Garter
Garter
Posts: 2
Joined: Mon Mar 12, 2007 2:13 am

Post by Melly1657 » Mon Mar 12, 2007 2:51 am

please help answer this question!

User avatar
LilKim
Coral
Coral
Posts: 436
Joined: Mon Mar 20, 2006 8:36 pm
Contact:

Post by 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?

2Loula
Garter
Garter
Posts: 11
Joined: Tue Mar 13, 2007 12:51 pm

Post by 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.

User avatar
loveangel
King Cobra
King Cobra
Posts: 1117
Joined: Wed Jul 05, 2006 11:52 am
Location: Philippines
Contact:

Post by 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..

User avatar
loveangel
King Cobra
King Cobra
Posts: 1117
Joined: Wed Jul 05, 2006 11:52 am
Location: Philippines
Contact:

Post by loveangel » Tue Mar 13, 2007 1:40 pm

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

User avatar
Revenged
Coral
Coral
Posts: 118
Joined: Sat Oct 07, 2006 10:27 pm

Re: Question

Post by 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...

User avatar
Revenged
Coral
Coral
Posts: 118
Joined: Sat Oct 07, 2006 10:27 pm

Post by 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...

User avatar
Dr.Stein
King Cobra
King Cobra
Posts: 3501
Joined: Thu Jul 07, 2005 7:58 am
Location: 55284 Yogyakarta, Indonesia
Contact:

Post by Dr.Stein » Tue Mar 13, 2007 11:48 pm

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

Pollination? :?
Image

Post Reply

Who is online

Users browsing this forum: No registered users and 4 guests