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Analyzing gel electrophoresis picture?!

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Analyzing gel electrophoresis picture?!

Postby annline » Mon Jul 04, 2011 7:32 pm

I just dont have any idea where I should start..
My exercise is; "Analyze this picture:"

I dont know what is the information I can get from the picture.. The first lane is size marker? How can I be sure that the material first place was DNA and not just some protein? (Can I say so because of that size marker?)
Is it like I should be able to tell that in lane2 the DNA fragment is bigger than in line3? Why there is two "hits" in line4?

I just dont understand at all.. Can you give me some hints where should I start? What information I could get from that pic? What "analyze" means in this situation..
gel_map.jpg (19.32 KiB) Viewed 7687 times
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Postby canalon » Mon Jul 04, 2011 9:05 pm

A few line for your quest to answers:
- How do you "see" the DNA in the gel? would the stain work with protein?
- Why is there a molecular weight marker? Use it for its intended use, as in draw a graph with Rf and Molecular weight, make precise measurements and give good results.
You probably have a little blurb explaining what are in the different lanes. If not there is not much you can say about the bands you observe. If you do you can try to discuss the results of that gel.

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
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Postby JackBean » Tue Jul 05, 2011 7:01 am

canalon: not exactly this staining, but you can always make a negative of your picture ;)

Cis or trans? That's what matters.
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Re: Analyzing gel electrophoresis picture?!

Postby patlangic » Mon Aug 08, 2011 8:19 pm

it looks like a picture representing RFLP analysis of a 250bp-long DNA fragment on which one polymorphic restriction cut site is located (at around 175th bp). these three samples should have been collected from three different individuals. lane2 and lane3 represents the two homozygous genotypes (let's say AA and aa) and the last lane represents the heterzygous phenotype (Aa). In AA genotype, that particular cut site is mutated at both loci so that the restriction enzyme cannot digest any of the strands. In aa genotype, both of the strands contain the intact cut site so that both of them could be digested with enzyme producing two smaller (around 175 bp- and 75bp-long) fragments. In Aa genotype, one of the strand is mutated so that it was not digested while the other was digested as in lane3.

Hope this helps..
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Postby patlangic » Mon Aug 08, 2011 8:26 pm

one correction to the previous message:

''...that particular cut site is mutated at both loci..''

i meant 'alleles' of course; presence of different loci have nothing to do with this case :)
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