With each PCR cycle there is an in the concentration of the

With each PCR cycle there is a(n) _____________ in the concentration of the DNA polymerase with respect to the concentration of template DNA.

Solution

With each PCR cycle there is a decrease in the concentration of the DNA polymerase with respect to the concentration of template DNA.

Depending on the ability, fidelity, efficiency to synthesize large DNA products, Taq polymerase is the most common DNA polymerase enzyme used in PCR technique.

The specific activity of most commercial preparation of Taq is approximately 80,000 units/mg of protein. Since the efficiency of primer extension with Taq polymerase is generally approx. 0.7, the enzyme becomes limiting when 1.4*1012 to 7*1012 molecules of amplified product have accumulated in the reaction.

PCR cycle:

Polymerase chain reaction or PCR is a technique used to make multiple copies of a segment of DNA in vitro. PCR is very precise reaction and can be used to amplify a specific DNA target from a mixture of DNA molecules.

First step: Two short DNA sequences called primers are designed to bind to the start and end of the DNA target.

Second Step: To perform PCR, the DNA template that contains the target is added to a tube that contains primers, free nucleotides, and DNA polymerase enzyme. This mixture is placed in a PCR machine.

Third Step: The PCR machine increases and decreases the temperature of the sample in automatic programmed steps. Initially, the mixture is heated to denature, the double-stranded DNA template into single strands. The mixture is then cooled so that the primers bind to the DNA template.

Fourth Step: The DNA polymerase begins to synthesize new strands of DNA starting from the primers. Following synthesis and at the end of the first cycle, each double-stranded DNA molecule consists of one new and one old DNA strand.

PCR then continues with additional cycles that repeat the above steps. The newly synthesized DNA segments serve as templates in later cycles which allow the target DNA to be amplified in an exponential manner to about millions of times.