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Daltonism

Daltonism

Inability to perceive or distinguish certain colours, especially. Red; colour blindness. It has various forms and degrees. So called from the chemist Dalton, who had this infirmity.


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Females heterozygous for X linked diseases

I know that female mammalians randomly inactivate one X chromosome in somatic cells.So, if a human female was daltonism carrier, would not she be half daltonic?Because, ~1/2 of her cells in retina would have a recessive allele and the other half would have the dominant allele?Or ...

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by kysa
Fri Jan 04, 2013 5:04 pm
 
Forum: Genetics
Topic: Females heterozygous for X linked diseases
Replies: 1
Views: 1355

Re: Daltonism exercice

You just need to find which combination would produce this effect. 1. ALL boys are affected. Therefore, BOTH of mother's "X" chromosomes carry responsible allele. 2. Mother is NOT affected. Therefore, she is heterozygous for "X". There is only one way to reconcile this with the f...

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by Cat
Tue Sep 27, 2011 8:27 pm
 
Forum: Genetics
Topic: Daltonism exercice
Replies: 1
Views: 2932

Daltonism exercice

... on three gens (Red, Green, Blue). Gens R and G are on the same sexual chromosome X while B is autosomal. The lost of any of this gens result in Daltonism (result of an homozygous genotype or hemizygous recessive). A daltonic man marries a non daltonic woman and they have 4 girls and 4 boys. ...

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by krosano
Fri Sep 23, 2011 4:03 pm
 
Forum: Genetics
Topic: Daltonism exercice
Replies: 1
Views: 2932

Re: Dihybrid cross involving two sex-linked genes

... So, punnett square shouldn't be used. But, we can still use it in some cases. Let me give you an example: A man has both illnesses (hemophilia and daltonism) and his wife is not ill or carrier for both of them. So, Man is (X^hd Y) and Woman is (X^HD X^HD). Punnett Square: ------------X^hd / Y X^HD......X^hd ...

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by DRT23
Wed Mar 30, 2011 9:33 am
 
Forum: Genetics
Topic: Dihybrid cross involving two sex-linked genes
Replies: 6
Views: 9920

Dihybrid cross involving two sex-linked genes

... in this case. But, Punnett square may be used in some situations like in a and can't be used in others like b: a) If a man has both hemophilia and daltonism > X^hd Y, no other possibility. It's also easy to predict genotypes of a woman who has both illnesses or none (while not being carrier). ...

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by DRT23
Mon Mar 28, 2011 6:31 pm
 
Forum: Genetics
Topic: Dihybrid cross involving two sex-linked genes
Replies: 6
Views: 9920
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