Quiz

1. Assuming you have four copies of your desired template DNA to start and you run a 25 cycle PCR, how many copies of DNA will you have at the end of the PCR (under optimal conditions)?
   a. 4 x 2²⁵

   b. 4 x 25²

   c. 1 x 25⁴

   d. 1 x 4²⁵
2. Prior to the introduction of DNA polymerase from the thermophilic bacteria Thermus aquaticus, DNA polymerase had to be introduced into the reaction fresh every cycle. Why was this the case and what was unique about Taq (Thermus aquaticus) DNA polymerase?
   a. Taq DNA polymerase is thermostable and does not denature at high temperatures.

   b. Taq DNA polymerase denatured at high temperatures, making it more efficient.

   c. Taq DNA polymerase synthesized DNA in a 3' to 5' direction.

   d. Taq DNA polymerase required no primers to synthesize DNA.
3. The three temperature cycles of a PCR (in order) are
   a. denaturation, synthesis, primer annealing.

   b. primer annealing, denaturation, synthesis.

   c. synthesis, denaturation, primer annealing.

   d. denaturation, primer annealing, synthesis.
4. When running PCR products on an agarose gel, DNA migrates from the negative (anode) to the positive (cathode) poles because
   a. DNA is supercoiled.

   b. DNA has a negatively charged phosphate backbone.

   c. DNA has a positively charged phosphate backbone.

   d. DNA is polarized.

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