Question : 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.

Question : What did Meselson and Stahl observe when They cultured E. c

1.	Question : 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.
Answer» Solution :Meselson and Stahl obsered that in the E. coli bacterium the DNA becomes completely labelled with `N^15` medium by CENTRIFUGATION forfew genretion ·After two genretion density changed and showedequal amount of light DNA(`N^14`) and dark HYBRID DNA `(N^14-N^15)`. They concluded that DNA REPLICATES semi-conservately.[For Figure See Q. 30. Set-I. Outside Delhi, 2008]. .RNA is the first genetic material. RNA is highly reactive, and acts as a catalyst as well as genetic material. ESSENTIAL life processes such as metabolism, translation and splicing evolved around RNA.