What is polymerase chain reaction and how can it be utilised for gym amplification

PCRPCR:

    The polymerase chain reaction multiplies copies of DNA or its segments in vitro using two sets of primers which are small chemically synthesized oligonucleotides complementary to the regions of DNA and an enzyme called DNA polymerase. The enzyme polymerase extend the primers is nucleotides provided in the reaction and the DNA Part provided as template. The process of replication can be repeated and a billion copies of the DNA can be multiplied. Thus a small fraction of DNA can be multiplied for study and used in genetic engineering.

PCR can it be utilised to gene amplification:

    The following procedure is applied for obtain multiple copies of DNA:

     At the start of PCR, the DNA from which a segment is to be amplified,an excess of the two primer molecules, the four deoxyriboside triphosphates and the DNA polymerase mixed together in the reaction mixture. The following operations and now performed as sequentially.

     Step1:

The reaction mixture is heated to a temperature that assures DNA denaturation.

      Step2: 

 The mixture is now cooled to a temperature that permits annealing of the primer to the complementary sequence in the DNA; this sequences are located at the 3 ends of the two strands of the desired segment. This step is called annealing.

     Step3:

The temperatures now so adjusted that the DNA polymerase synthesizes the complementary strands by utilising 3'-OH of the primers; this reaction is the same as that occurs in vivo during replication of the leading strands of the DNA duplex. The primers are extended towards each other so that the DNA segment lying between the two Primers is copied

     The completion of step 3 completes the first cycle of amplification each cycle may take few minutes.

     Step4:

The next cycle amplification is separated the newly synthesized DNA strand from the all DNA strands.

     Step5:

Annealing allows the primers to base pair with both the new and did strands, the total number of strands being twice their original number.

     Step6:

Synthesis of new Strands takes place, which Doubles the number of copies of the desired DNA segment present at the end of step 1, this completes the second cycle.

       Thus at each cycle, both new and old strands anneal to the Primers and serve as templates for DNA synthesis.  As a Result at the end of each cycle, the number of copies of the desired segment becomes twice the number of present at the end of the previous cycle. Thus at the end of N cycles 2N copies of the segment are expected; the real values are quite close to this expectation. The cycle may be repeated.