AIIMS November 2011 – MCQ 31

All of the following are required in PCR except
A. Deoxyribonucleotides
B. Thermostable enzyme
C. Dideoxyribonucleotides
D. DNA template

Correct answer : C. Dideoxyribonucleotides

A basic PCR set up requires several components and reagents. These components include:

• DNA template that contains the DNA region (target) to be amplified.
• Two primers that are complementary to the 3′ (three prime) ends of each of the sense and anti-sense strand of the DNA target.
• Taq polymerase or another DNA polymerase with a temperature optimum at around 70 °C.
• Deoxynucleoside triphosphates (dNTPs; nucleotides containing triphosphate groups), the building-blocks from which the DNA polymerase synthesizes a new DNA strand.
• Buffer solution, providing a suitable chemical environment for optimum activity and stability of the DNA polymerase.
• Divalent cations, magnesium or manganese ions; generally Mg²⁺ is used, but Mn²⁺ can be utilized for PCR-mediated DNA mutagenesis, as higher Mn²⁺ concentration increases the error rate during DNA synthesis
• Monovalent cation potassium ions.