DNA day 2 1A part 2 *The experiments

Question 1

Grffith

Answer 1

Found a substance that could genetically transform Streptococcus Pneumonia

Question 2

Avery Macleod and McCarthy

Answer 2

Identified DNA as the molecule that transforms rough S.Pneumonia to the infective form

Question 3

Hershey and Chase

Answer 3

Found the evidence establishing DNA as the hereditary molecule

Question 4

Streptococcus pneumoniae
Smooth strain (S) (5)

Answer 4

Bacterium is surrounded by a polysaccharide capsule

*Sugary coating

protects S strain from the immune system thereby allowing infection. Capsule invades and protects from immune attack.

Sugar used to confuse our body

Virluent

Question 5

Streptococcus pneumoniae
Rough strain (S) (2)

Answer 5

Lacks polysaccharide capsule, cannot evade the immune system therefore non virulent

No capsules and immune system can hunt it down

Question 6

Explain to me Griffith’s experiments

4 cases+ explain the findings+ important thing abt the transformation (6)

Answer 6

THE TRANSFORMING PRINCIPLE

There was four cases,

1. Mouse dies from smooth strain
2. Mouth remains healthy from rough strain
3. Mouse remains healthy from heat killed Smooth bacteria
4. Mouse dies when heat killed smooth is combined with nonvirulent rough strain

Findings: the DNA of the S strain have survived the heating process and taken up bu the R strain bacteria. The S strain DNA contains the gene that forms the smooth protective polysaccharide capsule. The former R strain now has this gene and is protected from the host’s immune system

Transformation was permanent and heritable

Question 7

Avery MacLeod and McCarthy Experiment + tell me about each tube + as well as prior to the mixing of enzyme
(6)

Answer 7

1. A cell extract cytoplasm of heat killed S cells contains proteins RNA and DNA
2. RNAse , Protease, and DNAse are added to each sample which destroys the RNA, Protein and DNA
3. The added enzyme solution is in contact with Rough strain cells
4. Tube 1: RNA gone but transformation occur so we know that RNA can’t be the molecule transforming R cells to S cells
5. Tube 2: Transformation occurs so proteins not responsible for transforming
6. Tube 3: No transformation of R cell occurred when DNA was destroyed therefore DNA is the transformation molecule

Question 8

Hershey and Chase (6)

Answer 8

1. Labelled bacteriophage DNA and proteins with radioactive isotopes 32P and 35S respectively.
2. DNA has phosphate and proteins have sulphur
3. allowed the infection of E.Coli with radioactive bacteriophage.
4. Separate attached bacteriophage and E. coli with blender
5. There was no protein injected into the E coli cell so the 35S was not present. There was 35 S found in detached bacteriophages
6. There was 32P in E coli cells and the offsprings they made but not in detached bacteriophages.

Question 9

Temperate bacteriophages

Answer 9

enter an inactive phase while inside the host cell and can be passed several generations before becomming active