Which of the following is not used in polymerase chain reaction?
(A) DNA Polymerase (B) Taq polymerase (C) Dideoxyribonucleotides (D) DNA template
(C) PCR is an in vitro DNA amplification procedure in which millions of copies of a paicular sequence of DNA can be produced within a few hours.The reaction cycle has the following steps:Step 1: Separation (Denaturation): DNA strands are separated (melted) by heating at 95degC for 15 seconds to 2 minutes.Step 2: Priming (Annealing): The primers are annealed by cooling to 50degC for 0.5 to 2 minutes. The primers hybridize with their complementary single-stranded DNA produced in the first step.Step 3: Polymerization: New DNA strands are synthesized by Taq polymerase. This enzyme is derived from bacteria Thermus aquaticus that are found in hot springs.The steps of 1,2 and 3 are repeated. In each cycle, the DNA strands are doubled. Thus, 20 cycles provide for 1 million times amplifications. These cycles are generally repeated by automated instrument, called Tempcycler.5. After the amplification procedure, DNA hybridization technique or Southern blot analysis with a suitable probe shows the presence of the DNA in the sample tissue.Dideoxyribonucleotides are not used in the polymerase chain reaction.