Alfred Hershey and Martha Chase studied how a virus
infects bacterial cells by attaching to the cells. They knew
the virus was made mostly of proteins and DNA. They
labeled the proteins with radioactive sulfur. They labeled
the DNA with radioactive phosphorus. The diagram below
shows Hershey and Chase's experimental setup.
Experiment 1
Experiment 2
Radioactive viral DNA
Virus
Mix in a flask,
blend, and then
separate with a
centrifuge.
Bacteria
Radioactive viral protein
Virus
Mix in a flask,
blend, and then
separate with a
centrifuge.
Bacteria
Fluid
Fluid
(lighter
Pellet
(lighter.
Pellet
viruses)
(heavier
viruses)
(heavier
bacteria)
bacteria)
How did Hershey and Chase know that DNA carries the
information that viruses transfer into bacteria?
A. Radioactive sulfur was found in both the pellet and the
fluid.
B. Radioactive phosphorus was found in the bacterial pellet.
c. They found that the radioactive sulfur disappeared in
the centrifuge.
D. Radioactive phosphorus was found in the fluid.
SUBMIT