SI SessionsMondays 6:00 p.m. - 6:50 p.m.Tuesdays 3:00 p.m. - 3:50 p.m.Wednesdays 6:00 p.m. - 6:50 p.m.Thursdays 2:30 p.m. - 3:20 p.m.

Griffith (Module 9, Slides 8-9)

Avery (Module 9, Slides 10-13)

Hershey and Chase(Module 9, Slides 14-18)

Transformation occurring in certain bacteria non-virulent cells were being transformed into virulent

Experimented with mice

Non-virulent (IIR) bacteria → lived but no bacteria was recovered Virulent (IIIS) bacteria → died and bacteria was recovered

Heat killed Type IIS → mice lives, no bacteria was recovered

Heat killed Type IIIS + living IIR → mouse dies and we recover IIIS

We did not recover rough bacteria because it transformed into smooth

Transforming principle/unknown agent → Slide 10

Identified the transforming agent from Griffith’s experiment and that the transforming agent was DNA

Slide 13'Because only DNase destroyed the transforming substance, the transforming substance is DNA'

Extractions→ detergents and organic solventsEliminate carbohydrates, lipids, and proteins

To prevent debris/cross contaminationHistones (chromatin proteins) wrap around DNA to help condense it in the nucleus

It made the mixture result in a nitrogen phosphorus ratio consistent with nucleic acid (Slide 28)

Showed that DNA is the infectious agent in bacteriophages through radioactive media and T2 phages

T2 phages→ viruses that infect bacteria (Module 8, Slide 17)

32P- found in the backbone of DNA → inside the virus

35S- corresponds to protein (Module 9, Slide 5) → labeled protein capsids (Module 9, Slide 16)

After infection, the empty phages are separated from the cells by blending

Analysis of the supernatant and the centrifuge

32P stayed inside the bacteria progeny

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1. Describe the following in regards to the Meselson-Stahl experiment:a. Gen 0: b. Gen 1: c. Gen 2:

2. What would the outcome of the experiment look like if DNA replicated in a conservative or dispersive way? How many bands would you see for each generation?

a. Gen 0:b. Gen 1:c. Gen 2:

3. How many origins of replication do bacteria need for the formation of a single replication bubble? What do we call the origin of a replication site in bacterial chromosomes?

4. What happens in a replication bubble in bacterial chromosomes?

5. True or False: Plasmids contain an origin of replication and a termination state.

6. True or false: DNA synthesis must occur in a parallel manner.

7. What’s the difference between 5’ and 3’ ends of DNA?

8. On the newly synthesized strand, to which end did DNA polymerase add nucleotides?

9. What’s the reverse process of 5’ → 3’ polymerization of DNA? What’s the purpose of this

10. For Prokaryotic DNA Polymerases fill in the following chart. For polymerases that can perform the action described, add a (+) in the space or add (-) if the polymerase cannot perform the action.

Properties I II III

5’ to 3’ polymerization

3’ to 5’ exonuclease activity

Initiate Chain Synthesis

5’ to 3’ exonuclease activity

11. Why must the incoming nucleotides be in the triphosphate form to generate the formation of a phosphodiester bond? What bonds are broken and what bonds are formed? What type of chemical reaction occurs?