Question

You are part of the science team studying life on Mars and just made a huge discovery: you have isolated a martian microbe, and it contains DNA as its genetic information! Your team decides to determine how the DNA is replicated. To do this, your team sets an experiment like the one used by Meselson and Stalh. Cells were grown in an N15 culture, then you transferred 10 cells (10 molecules of double-stranded DNA) to N14 media and grow them for 5 generations. If the Martian microbe replicates in a dispersive manner, what would be the number of double-stranded molecules that are 50% N14 and 50% N15 after 5 generations?

Answer 1

Ans.

20 molecules of double stranded DNA will be 50℅ N15 and 50℅ N14.

because in the dispersive manner of replication newly synthesized daughter strands have both parental and newly synthesized DNA.

In first round of replication there will be 20 daughter DNA strands replicated from 10 parental strands.

Hence first round of replication in these strands 50℅ part will be parental (N15) and 50℅ will be newly synthesized DNA (N14) in each strand.

As-