OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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E. coli cells grown on N-15 medium are transferred to N-14 medium and allowed to grow for 2 more generations. DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?
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one high-density and one low-density band
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One intermediate-density band
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one high-density and one intermediate-density band
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one low-density and one intermediate-density band
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Explanation:
Detailed explanation-1: -After two rounds of DNA replication, no high-density band formation is observed because the E. coli was moved to the 14N medium. Therefore, the given option is false.
Detailed explanation-2: -E. coli were grown on heavy 15N solution to give a higher than normal density to the parental DNA, 14N isotopes were then added to the heavy nitrogen to produce a lower density.
Detailed explanation-3: -Escherichia coli fully labelled with N15 is allowed to grow in N14 medium. The two strands of DNA molecule of the first generation bacteria have. Different density and do not resemble parent DNA. No worries!
There is 1 question to complete.