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Source of Taq Polymerase in Polymerase Chain Reaction Biology Certification Guide
Identify the PCR DNA polymerase source: Thermus aquaticus yields thermostable Taq polymerase vital for high-temperature DNA amplification cycles, unlike E. coli or Drosophila, key for General Biology exam mastery.
Question
Name the organism from which DNA polymerase is obtained that is used in Polymerase Chain Reaction (PCR).
A. Drosophila melanogaster
B. Escherichia coli
C. Thermus aquaticus
D. Homo erectus
Answer
C. Thermus aquaticus
Explanation
Taq polymerase, the DNA polymerase essential for PCR, is derived from Thermus aquaticus, a thermophilic bacterium isolated from Yellowstone hot springs that thrives at temperatures of 70-80°C. This enzyme’s thermostability allows it to withstand the high denaturation temperatures (around 95°C) required in each PCR cycle to separate DNA strands, eliminating the need to replenish the enzyme after every cycle unlike heat-labile alternatives from mesophilic organisms.
PCR’s development revolutionized molecular biology by enabling exponential DNA amplification through repeated cycles of denaturation, annealing, and extension, with Taq’s robustness making the process efficient and automated since its discovery in the 1970s, while options like Drosophila (a eukaryote), E. coli (mesophile), and Homo erectus (extinct human ancestor) do not yield suitable polymerases.