Question

Escherichia coli fully labelled with 15N is allowed to grow in 14N medium. The two strands of DNA molecule of the first generation bacteria have

• A. different density and do not resemble parent DNA
• B. different density but resemble parent DNA
• C. same density and resemble parent DNA
• D. same density but do not resemble parent DNA.

Answer 1

Answer: (A)

E. coli fully labelled with ,5N is allowed to grow in l4N medium. The two strands of DNA molecule j of the first generation bacteria have different density and do not resemble parent DNA. Meselson and Stahl, 1958 by using l4N and l5N continued that the replication of DNA in E-coli is semi-conservative in nature.