PCR Techniques · Pathology

In the context of PCR contamination, what is the role of Uracil-N-Glycosylase (UNG)?

  1. To synthesize dUTP from dNTPs
  2. To degrade prior PCR products containing dUTP
  3. To stabilize the Taq polymerase at high temperatures
  4. To increase the speed of the annealing step
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Correct answer: To degrade prior PCR products containing dUTP

UNG is used in a pre-PCR incubation step to eliminate 'carry-over' contamination. It cleaves uracil from DNA strands produced in previous runs (where dUTP was substituted for dTTP), preventing them from acting as templates.

Difficulty: Medium Question 12 of 20

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