What did Meselson and Stahl observe when
They cultured E. coli in a medium containing `""^15Nh_4CL` for a few generations and centrifuged the content?
they transferred one such bacterium to the normal medium of `NH_4Cl` and cultured for 2 genretion ?
What did Meselson and Stahl conclude from this experiment? Explain With the help of diagram
Which is the first geretic material? Give reasons in support of your answer.

Explanation

### Step-by-Step Solution:

1. **Introduction to the Experiment**:
Meselson and Stahl conducted an experiment to determine the mechanism of DNA replication. They used E. coli bacteria and cultured them in a medium containing ammonium chloride (NH4Cl) with a heavy nitrogen isotope, nitrogen-15 (N15).

2. **Culturing E. coli in N15 Medium**:
The E. coli were allowed to grow in the N15 medium for several generations. During this time, the bacteria incorporated the heavy nitrogen into their DNA, resulting in DNA that was denser than normal (which contains nitrogen-14, N14).

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