Answer: Meselson-Stahl experiment.
- A Griffith's transformation experiment
- B Hershey-Chase experiment
- C Meselson-Stahl experiment
- D Avery-MacLeod-McCarty experiment
Correct answer: C. Meselson-Stahl experiment
Explanation: Meselson and Stahl used 15N and 14N labelled E. coli DNA and density gradient centrifugation to confirm semiconservative replication.
Helicase unwinds the double helix at the replication fork; one new strand (leading) is synthesised continuously toward the fork, while the other (lagging) must be made in short, separate Okazaki fragments because DNA polymerase only adds nucleotides 5'→3'.
Concept context
DNA structure, replication, transcription, translation, the genetic code, and gene regulation (lac operon). The single most important chapter for NEET molecular biology.