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mendel basic genetic

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

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mendel basic genetic

Postby ismailco » Sat Feb 06, 2010 3:57 pm

If i want to cross between a ''full whilte'' and a ''full black' cows
Black x White
inorder to get a certain type of offespring cow/s color in the ''1st generation F1'' wither if it is full white or full black or a mix between the two of them ,how can i know the ''initial genetic structure'' or ''the alele combination' for the parents ,for ex :how can i know if the white parent is dminant (WW) or (Ww) color or even a recessive one (ww),same thing for the other black parent inorder to be sure about the result of the offespring genetic make up ?
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Postby JackBean » Sat Feb 06, 2010 5:16 pm

You need to know the phenotype ratio of the offspring, if it's 3:1, the one which makes 3 parts is dominant and the other recessive, if it is 1:2:1, they are co-dominant.
That is for the case, that both parents are homozygous. In the case they were heterozygous (at least one of them), it would be little different.
http://www.biolib.cz/en/main/

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Re: mendel basic genetic

Postby ismailco » Sat Feb 06, 2010 5:47 pm

Dear jack bean :
as i understood from you, the process of alele segregation is totally random so we can't predict the genetic make up of the offspring ,yes i agree about that but: i think your answerof 3:1 is regarding F2 not F1that i asked
what i want to know if the homologus black cross with homologus white
BB X WW
the result will be BW,BW,BW,BW .............ALL heterologus genotyope ,then we have to look to the dominant alele
if all resulted cowsare black then the dominant alele is the ''B'' ,while if all resulted cows are white then the dominant alele is ''W''
does that mean we can't see a mix- color ''black & white'' because one alele''either a balck one or a white one '' should be dominant over another ?? and it is impossible to dominate together ?
again iam asking about the F1generation
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Postby JackBean » Sat Feb 06, 2010 6:11 pm

sorry, you're right, what I wrote would be true for heterozygous parents

The mixed cow you could get e.g. the the gene for color would be on sex chromosome, than one is randomly inactivated in females and they can become mixed.

If you mix black and white, what do you get?
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Postby ismailco » Sat Feb 06, 2010 8:18 pm

Dear jackbeat:
As you mentioned :i should get a mixed cow color because the gene for color would be on sex chromosome, than one is randomly inactivated in females and they can become mixed
could you clarify please ?
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Postby jwalin » Sun Feb 07, 2010 3:32 am

use the recessive test cross
it isn't what you do that matters but it is how you do it
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Postby JackBean » Sun Feb 07, 2010 9:48 am

kolean is better with this :) anyway, as you know, in males you have XY and in females you have XX, that is females have two X, whereas males only one. To compensate this, one of the X chromosomes in females is randomly inactivated and thus you can get different colors around the body ;)
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Re: mendel basic genetic

Postby ismailco » Sun Feb 07, 2010 9:10 pm

Dear jackbean
i got your idea but does that mean the coat color trait is usually inherited in ''sex chromosome x & y '' ,so we will not a pure color in F1 as mendil mentioned
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Postby JackBean » Mon Feb 08, 2010 7:56 am

IF it was on X chromosome (and I don't say it really is, that would need some research on the internet;), than depends, what parents you have (it depends always of course), but the male can be only one-color (has only 1 X chromosome), while the female can be either one-color (being probably homozygous) or mixed (being heterozygous).
http://www.biolib.cz/en/main/

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