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Alleles and gene, are they same?

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

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Alleles and gene, are they same?

Postby rosdi » Fri Feb 11, 2005 4:31 am

hi! im confuse between alleles and gene. are they same? what is test-cross and what is it function?
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Postby RobJim » Fri Feb 11, 2005 5:12 am

A gene is a location on the DNA that codes for a protein. An allele is one possibility for that gene. For example, if there were one gene for eye color, then blue eyes would be one allele, and brown eyes another allele for the same gene. I think.

I think a test-cross is when you mate two organisms under controlled circumstances and see what happens. I'm not sure though.
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Postby biostudent84 » Fri Feb 11, 2005 6:39 am

A test-cross is forced mating of two organisms to test for different genes.
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Postby sq » Thu Feb 17, 2005 5:10 am

A test cross determines whether a particular characteristic of a plant or animal is homozygous dominant (pure bred) or heterozygous dominant (hybrid) It is done by doing a cross of an individual who's genotype is unknown, with a recessive individual to try to find out if one of the offspring produced will be recessive.
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Postby angela » Thu May 19, 2005 10:51 pm

heterozygous dominant
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Postby angela » Thu May 19, 2005 10:53 pm

sq wrote heterozygous dominant.
heterozygous can't be dominant because it contains both a dominant and a recessive
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Postby ScottishKevin » Fri May 20, 2005 12:24 pm

I was going over test-cross with my Biology teacher the other day and she put it into a simple form:

If she had a Guinea Pig which was black in coat colour, but she didn't know whether it was homozygous dominant, recessive or heterozygous, and mated it with her other white Guinea pig in which she knew was homozygous recessive, she would use the offspring to determine whether the black Guinea Pig was homozygous dominant, homozygous receissive or heterozygous.

Does that help? Probably not.. Lol. A little confusing and I'm not sure if that is completely correct- but I'm sure it was the example she used.
"When We Call Someone A 'Monster', We Don't Really Know Anything About Them And Catagorize Them As A Completely Different 'Species'"
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testcross?

Postby victor » Fri May 20, 2005 12:40 pm

Yup, that's right...we do testcross to determine one organism's allele...we can do it by mating the unknown organism's allele with another one which we've known that it's allele are homozygotus recessive. After the mating is done we will get the fillial and do some research to their phenotype. From the fillials' phenotype, we can determine what is the right allele for each of them, then at last, we can determine the unknown organism's allele (or maybe I can say it genotype).
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