Question

In an experiment, {E. coli is grown in a medium containing \({}^{14}NH_4Cl\) (\({}^{14}N\) is the light isotope of Nitrogen) followed by growing it for six generations in a medium having the heavy isotope of nitrogen (\({}^{15}N\)). After six generations, their DNA was extracted and subjected to CsCl density gradient centrifugation. Identify the correct density (Light/Hybrid/Heavy) and ratio of the bands of DNA in CsCl density gradient centrifugation:}

• A. Hybrid : Heavy, 1 : 16
• B. Light : Heavy, 1 : 31
• C. Hybrid : Heavy, 1 : 31
• D. Light : Heavy, 1 : 05

Hint:

DNA density gradients provide insights into replication patterns.

Answer 1

The Correct Option is C

After six generations in a medium with heavy nitrogen (\({}^{15}N\)), most DNA will incorporate \({}^{15}N\), resulting in heavy DNA. 
- The ratio of hybrid to heavy DNA will be 1:31 after centrifugation.
- After six generations in a medium with heavy nitrogen (\({}^{15}N\)), most DNA will incorporate \({}^{15}N\), resulting in heavy DNA. 
- The ratio of hybrid to heavy DNA will be 1:31 after centrifugation.