Question

What do you mean by semi-conservative method of DNA? Who proved it and how?

Answer 1

Hint: Semi-conservative DNA means DNA replicates and each strand acts as template to form new strand. It was experimentally proved by using radioactive nitrogen 14 and 15. It is the most important process that is to produce new DNA strands and cause variations in organisms.

Complete answer:
DNA (Deoxyribonucleic acid) is the stable genetic material which transfers from one generation to another. DNA replication is the process by which copies of DNA strands can produce. Semi conservative method of DNA is the method which explains that two original strands of DNA separate during replication and each strand serves as a template strand to form new DNA strands. It occurs in antiparallel directions. Two copies of the DNA molecule are produced by this, that's why it is known as semi-conservative replication. It contains one newly synthesized strand and one newly synthesized strand.
The model of semi-conservative DNA was anticipated by Nikolai koltsov. This structure was experimentally proved by James D. Watson and Francis Crick in 1953. It was confirmed by the experiment in which they use two radio-isotopes, nitrogen-15 and nitrogen-14. In the first observation a hybrid of 14 and 15 was observed but in the second cycle the hybrid remains the same but light DNA appears as well. This shows the semi-conservative behavior of the DNA.

Note: Semi-conservative replication of DNA is beneficial to DNA repair. The new strand of the DNA can modify itself. During conservative replication the two strands of the double helix remain together and produce copy composed of two new strands. Disruptive replication can produce two DNA copies both containing distinct regions of DNA. It contains either both original or both new strands.