THE MOLECULAR BASIS OF INHERITANCE
DNA REPLICATION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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all 15N14N (hybrid) DNA.
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half 15N15N DNA (heavy) and half 14N14N DNA (light).
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half 14N14N (light) DNA and half 15N14N (hybrid) DNA.
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all 14N14N (light) DNA.
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Detailed explanation-1: -Therefore, starting with 15N15N DNA in E. coli, after 60 minutes, the percentage of DNA with 15N15N, 15N14N and 14N14N will be 0%, 25% and 75% respectively.
Detailed explanation-2: -coli cells with 15N-dsDNA are incubated in medium containing 14N nucleotide. After 60 minutes, 60 E. coli cells will have DNA totally free from 15N.
Detailed explanation-3: -coli fully labelled with N15N15 is allowed to grow in N14N14 medium, then after fist genertion of replication one of the two strands would have N15 and the other strand would have N14. The two strands of DNA molecule of the first generation bacteria have different density and resemble parent DNA.
Detailed explanation-4: -When E. coli fully labelled with N15 is allowed to grow in N14 medium, then after first generation of replication one of the two strand would have N15 and other strand would have N14. The resulting molecule would have a density which is intermediate between N15 DNA and N14 DNA.