Question

The data obtained from the meselson–stahl experiment after one generation of replication eliminated the dispersive model of dna replication. True or False

Answer 1

Answer:

False

Explanation:

Meselson-stahl experiment: The experiment done by Meselson and Stahl demonstrated that DNA replicated semi-conservatively, meaning that each strand in a DNA molecule serves as a template while DNA replication for synthesis of a new, complementary strand.

The conservative model was eliminated because according to it, there would be 2 bands, one representing the parental DNA at one density and other representing the daughter DNA at a different density. The result from the Meselson–Stahl experiment after one generation was consistent with both the semi-conservative as well the dispersive model.

Answer 2

Given statement is false

Explanation:

According to dispersive model of DNA replication,DNA molecules are hybrids of parental and daughter DNA;In this model each individual strand is a combination of original and new DNA

Meselson and Stahl did an experiment on DNA replication using E.coli bacteria

• E.coli was grown in a medium containing heavy isotope of nitrogen,bacteria took up the nitrogen and used to synthesize new biological molecules,including DNA
• It was grown for many generations,the nitrogenous bases of the bacteria's DNA were all labelled with heavy nitrogen
• Bacteria were then switched to light nitrogen isotope and allowed to grow for several generations
• They then measured the density of the DNA using density gradient centrifugation
• This method separates molecules such as DNA into bands by spinning them at high speeds in the presence of another molecule, such as cesium chloride
• Each DNA produced two DNA molecules each with one new strand and one old strand called semi conservative replication(half of the parental DNA conserved in daughter DNA)
• Each DNA strand act as a template for synthesis of new strand
• Hence,dispersive model of DNA was eliminated and semi-conservative model of DNA replication was proved by the above experiment