Biology Forum Genetics Genetics Question

last updated by Revenged 17 years ago
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    • #7114
      Agronomy
      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!!!

    • #69795
      mehdi71000
      Participant

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

    • #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.

    • #69799
      Agronomy
      Participant

      thank you for ur help

    • #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?

    • #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

    • #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

    • #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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