Question

1. What occurs during the annealing stage of a PCR reaction?

   	A.	The reaction stops
   	B.	The DNA polymerase copies the template DNA
   	C.	The primers bind to the template DNA.
   	D.	The DNA strands separate

2. The PCR protocol that is currently used in laboratory was facilitated by a discovery of bacterium called Thermus aquaticus in a hot spring inside Yellowstone National Park, in Wyoming. This organism contains a heat stable form of DNA Polymerase known as Taq polymerase, which continues to function even after it has been heated to 95^oC. Why would such a heat stable polymerase be beneficial in PCR?

3. 	A.	Each cycle includes a hot saturation phase (95 ◦C), which allows the primers to anneal to the target DNA
   	B.	Each cycle includes a hot denaturation phase (95◦C), which separates the hydrogen bonds that hold the strands of template DNA together
   	C.	Each cycle includes a hot denaturation phase (95 ◦C), which activates the Taq polymerase
   	D.	Each cycle includes a hot denaturation phase (95 ◦C), which serves to sterilize the culture

Answer 1

1. What occurs during the annealing stage of a PCR reaction?

The primers bind to the template DNA.

During annealing stage of PCR (after denaturation of DNA), primers bind to the cDNA (DNA template).

2. Why would such a heat stable polymerase be beneficial in PCR?

Each cycle includes a hot denaturation phase (95°C), which separates the hydrogen bonds that hold the strands of template DNA together.

Heating at 95°C breaks down hydrogen bonds between nitrogenous bases of dsDNA to generate ssDNA (DNA template).