DNA replication is semiconservative Based on this principle

DNA replication is semi-conservative. Based on this principle if the original parent dsDNA is radioactively labeled, what is the final ratio of labeled strands to unlabeled strands after 4 rounds of division?

Solution

After 4 rounds of replication there will be 2^4 ds-DNA = 16 ds-strands.

Out of 16 , 14 will be labelled strands and 2 will be unlabelled strands.

So, final ratio of labeled strands to unlabeled strands after 4 rounds of division will be 14:2

Explanation :As per the semi-conservative method of DNA replication, the two original strands of the parental ds-DNA will be present in 2 cells after 1 st generation,each having one parental DNA strand.Accodingly after 4 generation that will come to 14 labelled ds-DNA and 2 unlabelled DNA.