Meselson and Stahls used which of the following types of centrifugation in their experiment which aimed to prove semiconservative nature of DNA?
Meselson and Stahls used which of the following types of centrifugation in their experiment which aimed to prove semiconservative nature of DNA?
The correct option is A Density gradient centrifugation
Meselson and Stahl tested the DNA replication hypothesis. They cultured bacteria in a 15N medium. 15N is a heavy isotope of nitrogen so the DNA synthesized has a heavy density. Then the bacteria were cultivated in a 14N medium, DNA was isolated at different times. After one replication cycle, the DNA was found to be of intermediate density. This result is consistent with the semiconservative replication model, according to which all DNA molecules will consist of one 15N-labeled DNA strand and one 14N-labeled DNA strand. After two replication cycles, two bands of DNA were seen, one of intermediate density and other having light density. This result is what the semiconservative model states i.e. half should be 15N-14N intermediate density DNA and half should be 14N-14N light density DNA. Thus the correct answer is option A.
Meselson and Stahl tested the DNA replication hypothesis. They cultured bacteria in a 15N medium. 15N is a heavy isotope of nitrogen so the DNA synthesized has a heavy density. Then the bacteria were cultivated in a 14N medium, DNA was isolated at different times. After one replication cycle, the DNA was found to be of intermediate density. This result is consistent with the semiconservative replication model, according to which all DNA molecules will consist of one 15N-labeled DNA strand and one 14N-labeled DNA strand. After two replication cycles, two bands of DNA were seen, one of intermediate density and other having light density. This result is what the semiconservative model states i.e. half should be 15N-14N intermediate density DNA and half should be 14N-14N light density DNA. Thus the correct answer is option A.
