Unit 3 Quiz

Question 1

Griffith

Answer 1

Identifying DNA as the Material of Hereditary
- worked with pathogenic S-strain and nonpathogenic R-strain Pneumococcus bacteria
- R-strain + heat killed S-strain –> mouse dies
- S-strain passed on its deadly properties to the live nonpathogenic R-strain
- Transforming Principle - something could cause bacteria to change from one type to another (ie. nonpathogenic to pathogenic)

Question 2

Avery

Answer 2

Identifying DNA as the Material of Hereditary
- identifying the “transforming principle”
- DNA caused the transformation of R strain into S strain so DNA is the transforming principle (not protein or RNA)
- proteinase, RNAse, DNAse added to heat killed S cells solution then R cells are added
- Disabling DNA prevents bacteria to transfer and results in no S cells

Question 3

Hershey and Chase

Answer 3

Identifying DNA as the Material of Hereditary
- P32 used to track DNA in nucleic acid
- S35 used to track protein on capsid of virus
- bacteriophage (infects bacteria)
- tagged phosphate in DNA and sulfur in protein
- labelled viruses infect bacteria
- blended to detach viruses form bacterial cells
- centrifuging forces bacterial cells to the bottom of the tube forming a pellet (bacteria is denser/heavier than virus)
- most of the P32 is in the pellet with the bacteria
- most of the S35 is in the supernatant fluid with the viruses
- radioactivity
- Hereditary material is carried in DNA because the P32 transferred to the bacteria in the pellet
- also called the blender experiment

Question 4

Chromosomes are composed of…

Answer 4

two macromolecules (proteins and nucleic acids)

Question 5

Why did scientists think protein was the cell’s hereditary material?

Answer 5

• more complex than DNA
• proteins composed of 20 amino acids
• nucleic acids composed of 4 nitrogenous bases