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Multiple Choice
Why is Taq polymerase used as the DNA polymerase in the Polymerase Chain Reaction (PCR)?
A
It is able to withstand the high temperatures used in PCR.
B
It has a higher fidelity than other DNA polymerases.
C
It can synthesize RNA as well as DNA.
D
It is the only polymerase that can initiate DNA synthesis without a primer.
Verified step by step guidance
1
Understand the role of DNA polymerase in PCR: DNA polymerase is an enzyme that synthesizes new DNA strands by adding nucleotides to a DNA template during the Polymerase Chain Reaction (PCR).
Recognize the conditions of PCR: PCR involves repeated cycles of heating and cooling to denature DNA, anneal primers, and extend new DNA strands. These cycles require enzymes that can function at high temperatures.
Identify the unique properties of Taq polymerase: Taq polymerase is derived from the thermophilic bacterium Thermus aquaticus, which thrives in hot environments. This enzyme is stable and active at the high temperatures used in PCR, typically around 95°C for denaturation.
Compare Taq polymerase with other DNA polymerases: While other DNA polymerases may have higher fidelity or additional functions, they often lack the thermal stability required for PCR, making Taq polymerase the preferred choice.
Clarify misconceptions: Taq polymerase does not synthesize RNA, cannot initiate DNA synthesis without a primer, and its fidelity is not necessarily higher than other polymerases. Its primary advantage is its ability to withstand high temperatures during PCR cycles.