Biology Ease Staff asked 2 years ago
The discovery of DNA replication is attributed to the famous experiments of Meselson and Stahl in 1958. They designed an experiment to determine the mode of DNA replication, whether it was conservative, semi-conservative, or dispersive.
In their experiment, they grew E. coli bacteria in a medium containing heavy nitrogen (15N) for several generations, which resulted in the incorporation of heavy nitrogen atoms into the DNA of the bacteria. Then they transferred the bacteria to a medium containing lighter nitrogen (14N) and allowed them to replicate for one or two generations.
After each generation, Meselson and Stahl extracted the DNA and separated it using ultracentrifugation. They found that after one generation of replication, the DNA formed a band intermediate between the heavy and light DNA, which suggested that the DNA replication was semi-conservative.
In the second generation, they found that the DNA formed two bands, one intermediate and one light, indicating that DNA replication is semi-conservative, and each newly synthesized DNA molecule contains one strand from the original DNA molecule.
This experiment provided strong evidence for the semi-conservative mode of DNA replication and laid the foundation for further studies on DNA replication.