BIO EXAM

Predict which injection(s) of the Griffith's experiments will kill the injected mice. Injection with

live, avirulent, non- encapsulated bacteria AND heat- killed, virulent, encapsulated bacteria.

In Vitro

petri dish/ no living organisms

What radioactive isotope would you select to label only the proteins of a virus (explain why!)?

sulfur (35S). (proteins contain sulfur in their R-groups)

In the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:

was an example of the genetic exchange known as transformation.

The first experimenters to use Griffith's transformation assay to identify the genetic material were:

Avery, MacLeod, and McCarty.

Transforming factor

DNA

The works of Griffith and Avery showed that

DNA is the genetic material.

The bacteriophages used in Alfred Hershey's and Martha Chase's experiments showed that:

DNA was injected into bacteria.

The radioactive material injected into the bacteria by the bacteriophages of Hershey-Chase indicated that

DNA, not protein is the genetic material.

Which of the following inspired Avery and his colleagues to perform the experiments demonstrating that the transforming principle in bacteria is DNA?

Griffith's experiments on smooth and rough strains of Streptococcus pneumoniae

Griffith's experiments were done with

Streptococcus pneumoniae.

In Vivo

Test with living organisms

Bacteriophage

Viruses that infect bacteria

The bacteria that Griffith worked with killed mice only if they had

a polysaccharide-rich capsule.

Oswald Avery and his collaborators showed that the 'transforming principle' of Griffith was

bacterial DNA.

In Griffith's experiments, harmless bacteria changed and caused disease when they were mixed with

dead, virulent bacteria.

What radioactive isotope would you select to label only the nucleic acid of a virus (explain why!)?

phosphorus (32P)

The radioactive material injected into the bacteria by the bacteriophages of Hershey-Chase was

phosphorus(32P).

When Griffith injected mice with a combination of live rough-strain and heat-killed smooth-strain pneumococci, he discovered that

the dead mice contained living smooth-strain bacteria

When the avirulent bacteria changed to virulent organisms in Griffith's experiments, they were said to be

transformed

In the Hershey-Chase experiment with bacteriophages,

viral DNA was shown to enter bacterial cells and cause production of new viruses within the bacteria