Describe the experiment that helped demonstrate the semi-conservative mode of DNA replication

Solution

Meselson and Stahl (1958) experimentally proved that the DNA replication is semi-conservative. It had the following steps;

1. E. coli bacterium was grown for many generations in a culture medium in which the nitrogen source contained heavy isotope N₁₅ , thus the labelling of bacterial DNA was done.

2. Later on these bacteria were cultured in N₁₄ non-radioactive isotope.

3. DNA was analysed to determine the distribution of radioactivity.
4. The experiment showed that one strand of each daughter DNA molecule was radioactive whereas the other was non-radioactive.
5. During second replication in N₁₄ medium, the radioactive and nonradioactive strand separated and served as a template for the synthesis of nonradioactive strands.
6. Out of four DNA molecules, two are completely non-radioactive and the other two have half of molecule as non-radioactive.
This showed that DNA replication is semi-conservative.

Some More Questions From Molecular Basis of Inheritance Chapter

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Molecular Basis Of Inheritance

Describe the experiment that helped demonstrate the semi-conservative mode of DNA replication

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