Chapter 16/17 - DNA & Genetic Material Flashcards
What are the 2 forms Streptococcus pneumoniae?
normal virulent nonvirulent
What form of Streptococcus pneumoniae causes pneumonia?
normal virulent
What form of Streptococcus pneumoniae does not cause pneumonia?
nonvirulent
What is the mutant form of Streptococcus pneumoniae?
nonvirulent
Streptococcus pneumoniae: What form am I? Referred to as the S form
normal virulent
Streptococcus pneumoniae: What form am I? Forms smooth colonies on a culture dish
normal virulent
Streptococcus pneumoniae: What form am I? lacks an enzyme needed to manufacture the polysaccharide coat
mutant, nonvirulent form
Streptococcus pneumoniae: What form am I? forms rough colonies.
mutant, nonvirulent form
Performed a series of simple experiments in which mice were infected with bacteria
Griffith
Mice infected with the ___________ form died from pneumonia
virulent S
Infection with the _________ form had no effect.
nonvirulent R
If the virulent S form is first killed with heat, what is the result?
infection does not harm the mice
Infecting mice with a mixture of heat-killed S form with live R form caused what?
pneumonia and death in the mice.
High levels of live S form bacteria were found in the ____ of ____
lungs of the dead mice.
When polysaccharide coat passes from the dead, virulent S bacteria to the live, coatless R bacteria in the mixture, permanently altering the coatless R bacteria into the virulent S variety this process is called?
transformation
Transfer of virulence from one cell to another
Transformation
Transfer of genetic material between cells
Transformation
Identified the substance responsible for transformation in Griffith’s experiment.
Colin MacLeod and Maclyn McCarty
What steps were used to identify the substance responsible for transformation :
- prepared the mixture of dead S Streptococcus and live R Streptococcus
- removed as much of the protein as they could from their preparation, eventually achieving 99.98% purity
- transforming activity was not reduced.
Transformation Principle: Oswald Avery, Colin MacLeod and Maclyn McCarty
After nearly all protein removal, transfromation activity was not ___________-
reduced
Transformation Principle: Oswald Avery, Colin MacLeod and Maclyn McCarty
The substance responsible for transformation resembled what?
dna
Extracting lipids and proteins did what to transforming activity?
did not reduce
Protein-digesting enzymes and RNA-digesting enzymes did what to transforming activity?
did not affect
DNA-digesting enzymes did what to transforming activity?
destroyed
Who demonstrated that phage genetic material is DNA?
Alfred Hershey and Martha Chase
Who labeled either protein capsule or DNA of bacteriophages with radioactive isotopes (32P and 35S)
Hershey and Chase (1952)
Hershey and Chase (1952): Experiments provided several lines of evidence that genetic material is actually stored in what?
DNA and not protein
Hershey and Chase deduced that _____, and not ______, constituted the genetic information that viruses inject into bacteria.
DNA
PROTEIN
Although the three-dimensional structure of the DNA molecule was not elucidated until Watson and Crick, it was known that it contained three main components which are :
a 5-carbon sugar
a phosphate (PO4) group
a nitrogen-containing (nitrogenous) base. The base may be a purine (adenine, A, or guanine, G), a two-ringed structure; or a pyrimidine (thymine, T, or cytosine, C), a single-ringed structure. RNA contains the pyrimidine uracil (U) in place of thymine.
