NEETZoologyMolecular Basis of Inheritance
Description Step/Result A. Growth of E. coli in 15NH4Cl medium 1. Proved semiconservative replication model B. Transfer to 14NH4Cl medium 2. Lighter DNA began to appear C. Centrifugation in CsCl density gradient 3. Incorporation of 15N into newly synthesized DNA D. DNA extraction and density measurement 4. Separation of DNA based on density differences
Options
- AA - 1, B - 2, C - 3, D - 4
- BA - 3, B - 2, C - 4, D - 1
- CA - 2, B - 1, C - 3, D - 4
- DA - 4, B - 3, C - 1, D - 2
Correct answer
B. A - 3, B - 2, C - 4, D - 1
Step-by-step solution
A - 3: Growth of E. coli in a medium containing 15NH4Cl resulted in the incorporation of the heavy isotope 15N into newly synthesized DNA. B - 2: After transferring E. coli to a 14NH4Cl medium, lighter DNA started to appear as replication continued. C - 4: Centrifugation in a CsCl density gradient was used to separate DNA molecules based on density differences. D - 1: The extraction of DNA and measuring densities through centrifugation provided the proof for semiconservative replication.