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Nucleotide repeats on DNA

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

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Nucleotide repeats on DNA

Postby leanbeans » Tue Aug 23, 2005 9:06 am

is the nucleotide repeat on one DNA strand of one chromosome the same as the one on the other homologous chromosome in a person?
I know there can be different segment repeats, for eg, there can be 3 nucleotides segment repeats on one DNA strand and 10 on the other. But for each segment, is the nucleotide sequence the same on both chromosomes or different?

thanks!
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Postby mith » Tue Aug 23, 2005 12:24 pm

Recall that homologous chromosomes are inherited from the two parents. therefore, there's no reason for them to have any similarities.
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Postby MrMistery » Tue Aug 23, 2005 5:39 pm

The only case where the nucleotide sequence would be the same for both chromosoms in all pairs would be if you are homozygous for every gene you have.. And if you are a girl... :lol:
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Postby sdekivit » Tue Aug 23, 2005 6:43 pm

MrMistery wrote:The only case where the nucleotide sequence would be the same for both chromosoms in all pairs would be if you are homozygous for every gene you have.. And if you are a girl... :lol:


but still then mutations can occur.
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Postby MrMistery » Wed Aug 24, 2005 8:53 pm

Indeed... Maybe both alleles will mutate the same way at the same time... The odds of it happening is 1 to a bilion bilions, but it could happen :D
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Postby b_d_41501 » Thu Aug 25, 2005 6:26 pm

The same exact mutation on two alleles.....................it would be a stretch to even classify this as possible. However, since there is a chance of this occurring (I wish I knew the exact possibility of this, but I don't feel like calculating the number at the moment) it would be possible nonetheless. 1,000,000,000,000+ bonus points to the person who finds this probability!!!
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Postby MrMistery » Thu Aug 25, 2005 6:58 pm

IF YOU REALLY NEED TO KNOW
The probability of mutation occuring naturally in one gene is one to 100.000. Since you have 2 alleles the probability of mutation at both alleles at the allele of YOUR choise would be (number of genes)sqweared times 100.000. How many points?
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Postby b_d_41501 » Thu Aug 25, 2005 7:03 pm

So 1 in 62,500,000,000,000?
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Postby sdekivit » Thu Aug 25, 2005 7:13 pm

MrMistery wrote:IF YOU REALLY NEED TO KNOW
The probability of mutation occuring naturally in one gene is one to 100.000. Since you have 2 alleles the probability of mutation at both alleles at the allele of YOUR choise would be (number of genes)sqweared times 100.000. How many points?


it depends on what kind of mutation. If it's a mutation where 1 nucleotide is replaced by another, you'll also need to take into account the chance of the other base that gets incorporated.
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Postby MrMistery » Thu Aug 25, 2005 7:27 pm

That is reallly splitting hears into 100000000000....
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