[Campbell Biology P.490] The discovery of the bacterium Thermus aquaticus in Yellowstone Nat... | Practice Question

The discovery of the bacterium Thermus aquaticus in Yellowstone National Park's hot springs revolutionized molecular biology. Which enzyme isolated from this thermophile is crucial for one of the most important DNA-based techniques, and why is its thermophilic origin valuable?

  • A: Reverse transcriptase; its heat stability allows cDNA synthesis at high temperatures.
  • B: Restriction endonuclease; its high specificity ensures precise DNA cutting during gene editing.
  • C: DNA ligase; its ability to join DNA fragments at high temperatures enables efficient cloning.
  • D: Taq DNA polymerase; its heat stability allows it to withstand the high temperatures required for DNA denaturation during PCR cycles.

Explanation

The enzyme isolated from Thermus aquaticus that revolutionized molecular biology is Taq DNA polymerase. Its crucial value lies in its heat stability: it can withstand the repeated cycles of high temperatures around 95°C needed to denature DNA during PCR without losing activity, which greatly simplified and automated the PCR process.