Question

Meselson and Stahl’s experiment proved ______.

Options

• Transduction

• Transformation

• DNA is the genetic material.

• Semi-conservative nature of DNA replication.

Answer 1

Meselson and Stahl’s experiment proved Semi-conservative nature of DNA replication.

Explanation:

The Meselson and Stahl experiment (1958) definitively proved that DNA replication is semiconservative, meaning each new DNA molecule consists of one original parental strand and one newly synthesised strand. By growing E. coli bacteria in heavy nitrogen (¹⁵N) and then switching them to a medium with light nitrogen (¹⁴N), the researchers used density gradient centrifugation to observe the DNA’s weight over generations. They found that after one generation, all DNA was of intermediate density (a hybrid of heavy and light), and after two generations, half the DNA was hybrid and half was entirely light, which confirmed that the parent strands separate and serve as templates for new matching strands.