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My girlfriend can clone DNA

Cool title, huh?

Aya just started working at a lab that does genetic engineering. She’s barely there a week, and already she’s cloned DNA. Here is a HUGE simplification of how it works (as much as my programmer’s brain managed to understand, with tons of errors I’m sure):

  1. Get a sample of DNA, this will be your template
  2. Prepare a solution with:
    1. Nuclease-free water – you want to make sure the water doesn’t contain any other DNA, or it might be cloned instead of the template
    2. Buffer solution – help create optimal conditions for the enzyme (more on this later)
  3. Add two specific primers, each is a completion of some known segment of the template. The size of each primer is usually about 24 bases.
  4. Add lots of DNTPs – these are the DNA monomers, the single building blocks of DNA
  5. Add a heat-stable enzyme such as Taq polymerase – this is the engine behind the entire reaction. It will latch on to the primers and run along the templates, adding DNTPs and building the DNA molecule.
  6. Put it all in a PCR machine
  7. Repeat about 30 iterations:
    1. Heat to 94-99 °C to make the DNA strands disconnect
    2. Cool down to 50-65 °C, so the primers can attach to the DNA strands
    3. Heat to 75-80 °C, which is the the optimum temperature for Taq polymerase
    4. The Taq polymerase finds the primers and then runs along the disjoint strands, collecting nucleotides from the solution and building the complementary strands

This process theoretically clones a segment of a single DNA molecule to about 230 identical molecules. Because the Taq polymerase sometimes fall off while building the strands, after the cloning she measures the length of the DNA molecules using Agarose gel electrophoresis. On that, another time perhaps.