Question

Can someone explain to me why C is the correct answer?

Suppose that you performed a version of the Hershey and Chase experiment, this time using ³²P-labeled viruses that insert their double stranded DNA into the DNA of the cells that they infect. The viral DNA is then treated as part of the cell's own DNA and is replicated during DNA replication and passed onto daughter cells when the cell divides. You infect a population of cells with the ³²P-labeled viruses, and then let the infected cells go through two generations of cell divisions. If you then examine the cells, you should find ³²P-labeled DNA in ____ of the cells.

a. none

b. about 1/4

c. about 1/2

d. about 3/4

e. all

Answer 1

Consider a single cell infected with 32-P labelled virus.It incorporates its double stranded DNA with cell possessing double stranded DNA .Now the infected cell possess both of its strands with 32 P.

Going to the first generation of replication through semi conservative replication,each strand having 32P synthesizes new strand without 32P.As a whole both cells possessed 32P in the first generation,but only single strand in each cell has 32P.

In the second generation single strand of each cell possessing 32P synthesizes new normal strand into one cell and normal strand of each cell synthesise another normal strand into one cell.so out of 4,two cells have 32P