1.5- Mesolson and Stahl Experiment

• Who conducted the melon stall experiment?

  Meselson and Stahl
• What characteristic shape of DNA did Watson and Crick propose?

  Double helix
• What was the main question Meselson and Stahl aimed to answer?

  How does DNA make a copy of itself?
• What are the three proposed models for DNA replication?

  • Semiconservative model
  • Conservative model
  • Dispersive model
• What does the semiconservative model propose about DNA replication?

  DNA splits and new strands are added
• What type of bacteria did Meselson and Stahl use in their experiment?

  1. coli
• What is heavy nitrogen's atomic mass compared to normal nitrogen?

  Heavy nitrogen has an extra neutron
• What happens to DNA containing heavy nitrogen in an ultracentrifuge?

  It moves to the bottom of the tube
• If E. coli is grown in heavy nitrogen, what will happen to its DNA after replication?

  It will contain hybrid strands
• What does the term "hybrid strand" refer to in the context of DNA replication?

  A strand containing both heavy and light nitrogen
• What were the results of the Meselson and Stahl experiment after several generations?

  • Generation 0: 100% heavy nitrogen
  • Generation 1: 100% hybrid
  • Generation 2: 50% hybrid, 50% light
  • Generation 3: 75% light, 25% hybrid
• What conclusion did Meselson and Stahl reach about DNA replication?

  DNA replicates by splitting and adding new strands
• What is the significance of the Meselson and Stahl experiment?

  It demonstrated how DNA replicates