MCQs: The Basic PCR Reaction: Answers

1) Taq Polymerase is a commonly used DNA polymerase in a PCR Reaction? T/F

True: Other thermostable DNA polymerases can also be used such as “Pfu polymerase” which has a lower error rate when generating DNA strands.

2) DNA melting involves disrupting the covalent bonds between complementary DNA sequences? T/F

False: DNA melting refers to the disrupting of hydrogen bonds between complementary DNA sequences.

3) Annealing of the primers occurs at the temperature of 50-65C? T/F

True: Annealing temperature usually 3-5 degrees below the melting temperature of the prinmers used.

4) Primers generally consist of 200-300 nucleotides? T/F

False: Primers usually consist of approximately 20 nucleotides.

5) In a PCR reaction, the DNA generated is itself used as a template for replication? T/F

True: This is the whole reason and concept behind the exponential increase in target DNA strand.

6) Primers all have the same melting temperature? T/F

False: Melting temperature of DNA strands, (including primers) dependent to some extent on the amount of Guanosine-Cytosine (GC) bonds, which generally have stronger bonds than Adenosine-Thymine (AT). Thus primers with higher GC content have higher melting temperatures.

7) The melting temperature is the temperature at which the DNA disintegrates into it’s separate nucleotides? T/F

False: It is the temperature at which complementary DNA strands separate.

8) Urea may assist DNA denaturation? T/F


9) The extension step usually occurs at a lower temperature than the annealing step? T/F

False: The temperature in the PCR reaction is usually increased slightly to optimise this step.

10) PCR was invented by Sir Francis Crick?

False: Crick involved with discovering the Double Helix structure of DNA. Discovery of PCR attributed to Kary Mullis in 1983.



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