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I Need Help understanding gametes, genotypes and phenotypes

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

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I Need Help understanding gametes, genotypes and phenotypes

Postby Jojo789 » Tue Oct 29, 2013 3:02 am

I am having trouble understanding how to figure out the ratio of genotypes and phenotypes.
The question says: There is an allele E which codes for unattached earlobes in humans. The allele e codes for the attached earlobes which do not hang free. If a ee male marries a Ee female what gametes could each parent produce? Father: Mother:

Second part of the question is: what possible genotypes could their children have? What possible Phenotypes?

I did a punnet square with Ee and ee to find the gamestes but I got the same answer for the second part of the question. Help me please im so confuse.
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Re: I Need Help understanding gametes, genotypes and phenotypes

Postby Jojo789 » Tue Oct 29, 2013 3:06 am

I do not know how to go about this question. A man who has type AB blood marries a women with type B blood (her genotype is I^Bi). What phenotypes and genotypes of children could they produce.


Would I do a punnet square with AB and Ii?
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Postby wildfunguy » Tue Oct 29, 2013 3:25 pm

The first question isn't about offspring, it's just about gametes. You don't need to draw a punnett square until the second question. You're doing more work than it is asking you to do.

Post Two:
lowercase i is recessive and uppercase I is dominant, but there are actually two codominant alleles. I^A is dominant allele for type A, and I^B is dominant allele for type B.
There is only an exception if the have the Bombay phenotype, which involves alleles (denoted h & H) in another part of the genome.
Individuals with the rare Bombay phenotype (hh) do not express H antigen (also called substance H), the antigen which is present in blood group O. As a result, they cannot make A antigen (also called substance A) or B antigen (substance B) on their red blood cells, whatever alleles they may have of the A and B blood-group genes, because A antigen and B antigen are made from H antigen.

https://en.wikipedia.org/wiki/Hh_antigen_system
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Postby Jojo789 » Wed Oct 30, 2013 1:01 am

so the first would have gametes of Ee, ee for the female and male

and the second question is a doing a punnet square with I^A and I^B with I^Bi
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Postby Jojo789 » Wed Oct 30, 2013 3:01 am

I am still not understanding the second question i don't know how to put the punnet square together
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Postby JackBean » Mon Nov 11, 2013 11:36 am

no, gametes are haploid, so it can be either E or e
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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