Semiconservative Replication of DNA was Established Experimentally By

Question

Semiconservative replication of DNA was established experimentally by
A) gel electrophoresis.
B) ultraviolet spectroscopy.
C) column chromatography.
D) density-gradient centrifugation.

Accepted Answer

Semiconservative replication of DNA was established experimentally by density-gradient centrifugation. In this technique, a heavy isotope of nitrogen (15N) was used to label the original DNA strands. After replication in a medium containing a light isotope of nitrogen (14N), the newly synthesized DNA strands had a density intermediate between the original heavy strands and the light medium, indicating that each contained one old and one new strand, supporting the theory of semiconservative replication. Gel electrophoresis, ultraviolet spectroscopy, and column chromatography are not the primary methods used to establish semiconservative replication.