OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Which of the following nitrogen isotope used as first to grow E. coli in meselson and stahl experiment
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12 N
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13 N
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14 N
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15 N
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Explanation:
Detailed explanation-1: -Meselson and Stahl grew E. coli in the 14N isotope environment for all subsequent bacterial generations, so that any new DNA strands produced were of a lower density than the original parent DNA.
Detailed explanation-2: -The DNA replication is semi-conservative is proved by an experiment conducted by Meselson and Stahl in 1958. To perform their experiment they use heavy nitrogen (15N) in E. coli.
Detailed explanation-3: -Meselson & Stahl reasoned that these experiments showed that DNA replication was semi-conservative: the DNA strands separate and each makes a copy of itself, so that each daughter molecule comprises one “old” and one “new” strand.
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