Class 10 - History of DNA Replication

Question 1

What were the theories of DNA replication? Explain the main features?

Answer 1

semiconservative (2 strand act as template for complementary strand

dispersive (hybrid of old and new strands)

conservative (original double helix is conservative and other helix is completely new)

Question 2

Why was the Meselson-Stahl Experiment (1956) important for DNA replication?

Answer 2

MS labeled DNA of Ecoli bacteria across generations using isotopes of nitrogen (Started with heavy 15-N for a few generations and then switched to light 14-N)

Question 3

How did M-S prepare the DNA in their experiment?

Answer 3

The isolated 15-N DNA and loaded into a centrifuge tube. They did the same for 14-N DNA.

The centrifuge at high speed for 48 hours forms a cesium chloride