Electrophoresis Mind Map

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  • Electrophoresis separates DNA fragments
    • Based on size, can separate fragments different by only one base in length.
    • Gel slab contains agarose + buffer solution. Electrodes attached to each end so a current can be passed through.
    • Separation of strands of different lengths occurs because longer stands get caught in the agarose gell and are slowed, but shorter strands can move more quickly.
    • Basic Procedure
      • 1. DNA samples treated with restriction enzymes
        • 2. Placed into wells cut into   -ve electrode end of gel
          • 3. Electric current passed through for fixed time
            • 4. DNA attracted to +ve electrode (diffuse)
              • 5. Dye stains DNA
    • Fragments lifted from gel for further analysis.
      • Southern Blotting: nyon or nitrocllulose sheet placed over gel,
    • DNA can be labelled with a radioactive marker before the samples are run. Placing photographic film over the nitrocellulose sheet shows positions
    • A DNA probe is a short single strand of DNA (50-80 nucleotides long) complementary to specific section of DNA
      • Radioactive marker - detected by exposure to photographic film
        • Annealing - binding by complementary base pairing
          • Flourescent marker - detected by UV light
          • Locate gene for genetic engineering
          • Genome comparison
          • Genetic disease diagnosis
            • Probes placed on a fixed surface - DNA microarray
            • Amplified using PCR
      • Flourescent marker - detected by UV light


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