Question

Define and explain their function in a PCR Reaction

a) DNA polymerase

b) Primers

c) dNTPs

d) MgCl2

e) DNA

Answer 1

a) DNA polymerases are enzymes that synthesize DNA drom deoxyribonucleotides. In a PCR reaction, the most common DNA polymerase used is Taq polymease because it is heat stable. Its function is to add nuleotides to the 3' end of the DNA strand thereby helping to synthesize new strand of DNA complimentray to the target strand.

b) Primers are short strands of DNA or RNA that serve as the starting point of DNA synthesis. In a PCR reaction, DNA polymerases add nuleotides to the existing nucleotides which are provided by the primers.

c) dNTPs are the four deoxynucleotide triphosphates namely dATP, dGTP, dCTP, d TTP. These serve as building blocks supplying the respective bases to the DNA polymerase for DNA synthesis.

d) MgCl2 acts as a cofactor during the reaction process. Taq polymerase is a magnesium dependent enzyme, therefore MgCl2 is required functioning of DNA polymerase. It also acts as a catalyst that speeds up the chemical reaction.

e) DNA serves as a template. It contains the region that needs to be amplified. The primers attach to the template DNA and serve to amplify it.