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DNA

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

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DNA

Postby TsukiMarx » Tue Mar 09, 2010 9:54 pm

What is the relationship between DNA, chromosomes, genes and alleles?
this is a little difficult to piece together...
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Postby plasmodesmata11 » Wed Mar 10, 2010 1:03 am

dna makes up chromosomes, chromosomes contain genes, and alleles are varieties of genes
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Postby akki313 » Sun May 16, 2010 6:21 pm

Here's the order arrangement:
DNA combines to give genes.. which further combines to give alleles.. thousands of alleles constitute a chromosome ..
DNA - >genes - > alleles -> chromosomes..
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Re:

Postby JackBean » Sun May 16, 2010 8:03 pm

akki313 wrote: genes.. which further combines to give alleles..

not at all!!! Alleles are versions of genes!
http://www.biolib.cz/en/main/

Cis or trans? That's what matters.
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Postby ark » Sat May 22, 2010 12:22 pm

A chromosome consists of,except in RNA viruses, a DNA. Such a DNA contains multiple genes coding specific products ( polypeptides, RNA).Alleles are different forms (variants) of a gene.
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Postby jwalin » Sat May 22, 2010 5:29 pm

hmm the following will help
chromosome is made of 2 chromatin each of which is made by one single DNA
DNA has many genes on it
genes are made up off nucleotides

now alleles hmm its just the alternative form of genes
for example: lets say a plant has TT or Tt if its tall and tt if its short.
now in this the gene is the alphabet "t" while the allele is the capital or the small "t"
it isn't what you do that matters but it is how you do it
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Postby simina » Thu Feb 14, 2013 1:41 pm

Can you help me understand what exactly is nucleosome periodicity? We are studying it by adding micrococcal nuclease within the nucleus and studying it by SDS-PAGE.The results we had, showed several bands around 6 (nucleosomes that were cut by the nuclease). I do not really know how to interpret the results caz I do not understand what they mean by periodicity (this is supposed to analise it from the SDS-PAGE photo). Any ideas?
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Postby jonmoulton » Thu Feb 14, 2013 4:32 pm

I think this is a case where winding the DNA onto histones protects it from the nuclease, so the DNA is cut only in regions between the histones. If the same length of DNA is wound around each histone and every DNA segment between histones gets cut, the fragments after inter-histone degradation would be roughly the same size. Perhaps the nuclease doesn't cut between every histone; then you would see some double-length fragments, triple-length fragments etc. If you run the fragments out on a gel you would see a ladder and analysis of the masses of the ladder rungs would reveal that they are integer multiples of the mass of the smallest rung -- that is, the masses are periodic.

I've not done this. Anyone have experience with nucleosome periodicity?
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Postby simina » Fri Feb 15, 2013 2:38 pm

That is more clear for me thank you. Some bands are indeed a bit bigger than others, although it is not very clear!
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