1. DNA and RNA
Chapter 12

2. Griffith and Transformation

3. Griffith hypothesized…
when live, harmless bacteria and heat-killed bacteria were mixed, some factor was transferred from the heat-killed cells into the live cells
The ability to cause disease was inherited by the transformed bacteria’s offspring,
Transforming factor might be a gene

4. Avery’s Experiment

5. Avery and DNA
Avery and colleagues made an extract from the heat-killed bacteria then treated it with enzymes that destroyed proteins, lipids, CHOs, and RNA
Transformation still occurred
When DNA was destroyed, transformation did not occur
DNA stores and transmits the genetic information from one generation of an organism to the next

6. **The Hershey-Chase Experiment

7. Hershey and Chase concluded…
the genetic material of the bacteriophage was DNA, not protein

8. The Structure of DNA nucleotides Phosphate Nitrogen deoxyribose group
base

9. Nitrogen Bases

10. Chargaff’s Rules
[A] = [T] and [G] = [C]

11. X-Ray Evidence
Rosalind Franklin used x-ray diffraction to learn about the structure of DNA

12. The Double Helix F. Crick and J. Watson (1953)
2 strands wound together
Hydrogen bonds form between certain bases with just enough force to hold 2 strands together
A T
G C
Base pairing principle explained (Chargaff)