Genetics Question

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

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Agronomy
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Genetics Question

Post by Agronomy » Tue Mar 06, 2007 11:44 pm

All strains of Arabidopsis thaliana carry repeated sequences such as (ATATATATAT)n, where n varies within the genome of each strain. You performed the following experiments: (i) chose three wild-type strains; (ii) extracted genomic DNA from each strain; (iii) digested the DNA with a restriction enzyme; (iv) electrophoresed the digested products on an agarose gel; (v) transferred the DNA fragments onto a nylon membrane; (vi) prepared a 6-mer (base pairs) probe complementary to the repeated sequences ; (vii) hybridized the membrane with the probe; (viii) stained the membrane with NBT/BCIP complex. The membrane is shown in the handouts. Assuming that there is no mistake or technical problems in the Southern transfer, explain why banding patterns are not the same in lanes 1, 2, and 3.

I am really lost on this question? Any help would be great!!!

mehdi71000
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Post by mehdi71000 » Wed Mar 07, 2007 2:58 pm

is it saiying why is speacies 1,2 & 3 have diffrent dna strands?

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Post by Vagabond » Wed Mar 07, 2007 3:42 pm

Lanes 1, 2 and 3 are different (different sizes) because they are reflecting the different lengths of the dinucleotide repeat (ATATATATAT)n.

You state that you have 3 different strains.
You state that each strain carries a different length of repeats.

Typically the experiment is set up to enzymatically digest out a fragment that contains the repeat.
So strain 1 has 2 repeats
Strain 2 has 4
and Strain 3 has 8.
Run the gel strain 1 runs faster (smallest) and Strain 3 runs slowest (largest). Probe it and all bands containing the repeat core (your probe) light up.

Bing different size bands.
---------------------------------------

You know dog spelled backwards is god.
Coincidence? I think not. . .

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Post by Agronomy » Wed Mar 07, 2007 5:18 pm

thank you for ur help

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Post by Agronomy » Tue Mar 20, 2007 6:47 pm

I have another question though, I have attached a picture of the membrane. Can you explain why the banding patterns are different in the three different lanes?

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Southern Blotting II

Post by Agronomy » Tue Mar 20, 2007 6:52 pm

I have another question though, I have attached a picture of the membrane. Can you explain why the banding patterns are different in the three different lanes?

file:///C:/Documents%20and%20Settings/Pooja%20Manjunath/Desktop/Southern%20Blotting%20II.bmp

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Post by Agronomy » Tue Mar 20, 2007 7:05 pm

this is the picture, sorry I didn't know how to put it on the website...

http://photos-697.ak.facebook.com/ip002 ... 7_9869.jpg

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Post by Revenged » Wed Mar 21, 2007 2:31 pm

Binding patterns are different in the three lanes becaue the size of the DNA fragments is different...

Gel electrophoresis - smaller fragments travel further than larger ones... how do i remember this... rabbits travel futher than elephants because there are trees in the way...

;)

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