Q. 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. 6.3 RNA World
Explanation
Experimental material in the study of DNA replication has been Escherichia coli. E. coli fully labelled with 15N is allowed to grow in 14N medium. The two strands of DNA molecule of the first generation bacteria have different density and do not resemble parent DNA. Meselson and Stahl, 1958 by using 14N and 15N confirmed that the replication of DNA in E. coli is semi-conservative in nature.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.