Dominant and Recessive alleles

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Sora
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Dominant and Recessive alleles

Post by Sora » Sun Feb 10, 2008 8:22 pm

I have an exam on wednesday about genes, punnett squares, gene maps, etc.
I have trouble understanding Independent Assorment, Incomplete Dominance, Codominance, Multiple Alleles, and Polygenic traits.

Also, for punnett squares, I'm still not clear on genotypic ratios and phenotypic ratios.
What is the difference between them?

This is the punnett square from my practice questions:
B b
B BB Bb

b Bb bb

My guess is that the genotypic ratio is 1:2:1 and ..I'm not so sure about the phenotypic ratio.
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lozerface16
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Post by lozerface16 » Sun Feb 10, 2008 8:28 pm

ugh i have the same issue!!!!
but i have to find the possible phenotype of the offspring in a proportion!
it is all so confusing pleh...
You were born an original , don't die a copy....

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Post by smalik » Sun Feb 10, 2008 8:38 pm

Lets say the trait is Attached ears or Free ears. Where Free(B) is dominant, and (b) is reccesive.

The phenotype ratio is 1 carrier: 2 dominant: 1 recessive.

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Re:

Post by Sora » Sun Feb 10, 2008 8:47 pm

lozerface16 wrote:ugh i have the same issue!!!!
but i have to find the possible phenotype of the offspring in a proportion!
it is all so confusing pleh...



yeah, I know.
I wish I could help, but I don't know myself either. :cry:
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Re:

Post by Sora » Sun Feb 10, 2008 8:49 pm

smalik wrote:Lets say the trait is Attached ears or Free ears. Where Free(B) is dominant, and (b) is reccesive.

The phenotype ratio is 1 carrier: 2 dominant: 1 recessive.



Oh, okay
I think I get it a little better now..thanks

So, the 2 dominant is the BB, Bb, Bb
and the recessive is bb?
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lozerface16
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Re: Dominant and Recessive alleles

Post by lozerface16 » Sun Feb 10, 2008 10:10 pm

:evil: ugh i am so going to fail this test...............
You were born an original , don't die a copy....

Sora
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Re: Dominant and Recessive alleles

Post by Sora » Sun Feb 10, 2008 11:07 pm

lozerface16 wrote::evil: ugh i am so going to fail this test...............


\
aww :cry:
When is your test?
Tomorrow?
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Re: Dominant and Recessive alleles

Post by cracked_doc » Mon Feb 11, 2008 2:20 pm

So, the 2 dominant is the BB, Bb, Bb
and the recessive is bb?


the genotypic ratio will be : 1:2:1 as in 1 dominant (BB): 2 carriers (Bb): 1 recessive (bb)

BB is called dominant homozygous as it has both the dominant alleles for a character
Bb will also show same phenotype as BB but its called heterozygous as the two alleles are different

both will show the phenotype B

bb on the other hand will have phenotype b (for whatever traits you are discussing)

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Re: Dominant and Recessive alleles

Post by lozerface16 » Mon Feb 11, 2008 8:25 pm

Sora wrote:
lozerface16 wrote::evil: ugh i am so going to fail this test...............


\
aww :cry:
When is your test?
Tomorrow?


yeah it was today....... :cry:
i hope i did at least decent on it.... :?
You were born an original , don't die a copy....

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Re: Dominant and Recessive alleles

Post by Sora » Mon Feb 11, 2008 9:33 pm

cracked_doc wrote:
So, the 2 dominant is the BB, Bb, Bb
and the recessive is bb?


the genotypic ratio will be : 1:2:1 as in 1 dominant (BB): 2 carriers (Bb): 1 recessive (bb)

BB is called dominant homozygous as it has both the dominant alleles for a character
Bb will also show same phenotype as BB but its called heterozygous as the two alleles are different

both will show the phenotype B

bb on the other hand will have phenotype b (for whatever traits you are discussing)



Oh, thank you for explaining. :D
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Re: Dominant and Recessive alleles

Post by Sora » Mon Feb 11, 2008 9:34 pm

lozerface16 wrote:
Sora wrote:
lozerface16 wrote::evil: ugh i am so going to fail this test...............


\
aww :cry:
When is your test?
Tomorrow?


yeah it was today....... :cry:
i hope i did at least decent on it.... :?




Oh, I'm sure you did well.
As long as you tried your best. :)
"It is our destiny to attempt the impossible, to accomplish great deeds regardless of fear."
-Saphira (Eragon)

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lozerface16
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Re: Dominant and Recessive alleles

Post by lozerface16 » Tue Feb 12, 2008 11:56 pm

aww :cry:
When is your test?
Tomorrow?[/quote]

yeah it was today....... :cry:
i hope i did at least decent on it.... :?[/quote]



Oh, I'm sure you did well.
As long as you tried your best. :)[/quote]


lol i took the whole class period :P
i better have done well
i will find out tomorrow!!
You were born an original , don't die a copy....

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