Question

 

What is a thermal cycler?

What happens during the following steps: denaturation, annealing, extension?

 

What is the end goal of doing a PCR?

Answer 1

THERMAL CYCLER is an apparatus with help of which DNA segments can be amplified in PCR.

Consider it as an tank in which we can add all raw material for PCR and get the desired result this tank can survive extreme temperatures and provide safety for the process

The end goal of PCR is to produce large no. of copies of DNA i.e. amplify a small part of DNA for ease of study. At present a variation of PCR that is RT-PCR is used for corona virus testing.

The essential requirements for PCR are listed
below 1. A target DNA (100-35,000 bp in length). 2. Two primers (synthetic oligonucleotides of
17-30 nucleotides length) that are complementary to regions flanking the target DNA.
3. Four deoxyribonucleotides (dATP, dCTP, dGTP, dTTP).

4. A DNA polymerase that can withstand at a temperature up to 95oC (i.e., thermostable). The actual technique of PCR involves repeated cycles for amplification of target DNA.

The PCR is a method of amplifying a target sequence of DNA. 1. Denaturation : On raising the temperature
to about 95oC for about one minute, the DNA gets denatured and the two strands separate. 2. Renaturation or annealing : As the temperature of the mixutre is slowly cooled to about 55oC, the primers base pair with the complementary regions flanking target DNA strands. This process is called renaturation or annealing. High concentration of primer ensures annealing between each DNA strand and the primer rather than the two strands of DNA

3. Synthesis or extension The initiation of DNA synthesis occurs at 3'-hydroxyl end of each primer. The primers are extended by joining the bases complementary to DNA strands