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MBBS QUESTION #10371
Question 1
The polymerase chain reaction (PCR), used to exponentially amplify a specific target DNA sequence in vitro, consists of which three essential, repeated cyclic steps?
  • Denaturation (strand separation), annealing (primer binding), and extension (elongation)✔️
  • Transcription, translation, and replication
  • Ligation, restriction enzyme digestion, and gel electrophoresis
  • Centrifugation, filtration, and chemical precipitation
Correct Answer Explanation
Each PCR cycle involves heat denaturation of double-stranded DNA, annealing of short complementary primers to the target sequence at a lower temperature, and extension of new DNA strands by a heat-stable DNA polymerase (e.g., Taq polymerase) — repeated cycles exponentially amplify the target sequence, forming the basis of modern molecular diagnostics.