Genetics Question

March 6, 2007 at 11:44 pm #7114

Participant

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!!!

March 7, 2007 at 2:58 pm #69795

mehdi71000

Participant

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

March 7, 2007 at 3:42 pm #69797

Vagabond

Participant

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.

March 7, 2007 at 5:18 pm #69799

Agronomy

Participant

thank you for ur help

March 20, 2007 at 6:47 pm #70291

Agronomy

Participant

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?

March 20, 2007 at 6:52 pm #70292

Agronomy

Participant

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

March 20, 2007 at 7:05 pm #70294

Agronomy

Participant

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

March 21, 2007 at 2:31 pm #70328

Revenged

Participant

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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