Dna Replication

Step 1: Meselson and Stahl’s experiment is a landmark experiment that demonstrated the semi-conservative replication of DNA. The experiment used nitrogen isotopes (heavy nitrogen) and (light nitrogen) to label the DNA strands.

Step 2: In the experiment:
- The parental DNA was initially grown in a medium containing .
- After one round of DNA replication in , the newly synthesized strands contained , while the parental strands retained the label.
- In subsequent generations, the proportion of DNA containing only increases, while the amount of DNA with both and decreases.

Step 3: Analysis of DNA after 80 minutes (till III generation):
- In the first generation, the DNA will be of the type (one strand of and the other strand of ).
- In the second generation, DNA of type will appear along with the DNA of type .
- In the third generation, the ratio will be dominated by and in a 1:8 ratio, with the DNA of type being absent.

Step 4: Conclusion:
Thus, the ratio of DNA containing in the medium after 80 minutes will be 0:1:8.
Hence, the correct answer is option (C).