Meselson

Definition

Meselson, along with Franklin Stahl, conducted an experiment in 1958 that provided strong evidence for the semi-conservative model of DNA replication. Their work demonstrated that each new DNA molecule consists of one old and one new strand.

5 Must Know Facts For Your Next Test

1. The Meselson-Stahl experiment used E. coli bacteria and nitrogen isotopes to differentiate between old and new strands of DNA.
2. Their method involved growing E. coli in a medium containing heavy nitrogen (15N) and then switching it to a medium with light nitrogen (14N).
3. They utilized density gradient centrifugation to separate DNA based on its density, allowing them to observe the distribution of old and new DNA strands after replication.
4. Their results showed that after one round of replication, DNA consisted of hybrid molecules, supporting the semi-conservative model.
5. The experiment conclusively ruled out both conservative and dispersive models of DNA replication.

Review Questions

Related terms

Semi-Conservative Replication: A model of DNA replication where each daughter molecule contains one original strand and one newly synthesized strand.

Density Gradient Centrifugation:

A technique used to separate molecules based on their densities using a centrifugal force.

Nitrogen Isotopes (15N and 14N): Heavy (15N) and light (14N) forms of nitrogen used by Meselson and Stahl to label old and new strands of DNA.