- The graph shows results of an experiment by Hershey and Chase in 1952, in which bacteria were infected with a mixture of virus particles labelled with ³²P or ³⁵S isotopes. A suspension of the infected bacteria was agitated with a blender, and samples collected from the suspension were centrifuged to record the percentage of isotope remaining directly outside of the cells.
(a) Calculate the difference between the percentages of ³⁵S and ³²P remaining outside bacterial cells at 2 minutes. [1]
(b) Explain how this data provides evidence that DNA is the genetic material of cells. [3]
(c) (i) Draw a labelled diagram to show the structure of a DNA nucleotide. [3]
(ii) List the DNA nucleotides that are purines and pyrimidines. [1]
Purines:
Pyrimidines: