1. DNA and Protein Synthesis

2. What is DNA?
Contains the genetic information for making all the proteins in the cell

3. In the Beginning…..
The world of science debated on what the genetic material was
Some thought it was protein
Others believed it was DNA

4. Evidence for a Genetic “Factor”
1928 – Frederick Griffith’s “Transforming Factor” Experiment
Conclusion: “Something” from Heat-treated Strain 1 “transformed” Strain 2 to become deadly

5. DNA is Proven to be that Genetic Factor
1944 – Oswald Avery and colleagues focused on two of the genetic factor candidates: protein and DNA
Repeated Griffith’s experiment, but with a modification  
Proteases
Mouse dies  
DNases
Mouse lives
Conclusion – DNA is the transforming, thus genetic material

6. Avery Questioned In the Scientific Community

7. Final Proof that DNA is the Genetic Material
1952 – Hershey-Chase Experiment
Virus = DNA (inside) + protein (outside)
Conclusion: DNA was the genetic material due to viruses passing on DNA for reproduction

8. The DNA “Twist” DNA is a double helix
Every 10 nucleotides there is a 360 degree rotation
The structure of DNA is accredited to James Watson, Francis Crick and Rosalind Franklin

9. Frame of Reference
Where is the DNA located in eukaryotes? Prokaryotes?

10. The Structure of DNA DNA = deoxyribonucleic acid
DNA is a polymer built up from monomers
Monomers are called nucleotides

11. The Structure of DNA Continued
Phosphate Group – provides the “backbone” of DNA 5’ end (5 prime end)
Sugar – called a deoxyribose; also part of the DNA “backbone” 3’ end (3 prime end)
Backbone of DNA called the sugar-phosphate backbone

12. Nitrogenous Bases of DNA
Two Types
Pyrimidines  Thymine (T)
 Cytosine (C)
Purines  Adenine (A)
 Guanine (G)
Purines are double ringed, pyrimidines are single ringed

13. Pairing of Bases In DNA G hydrogen bonds with C
T hydrogen bonds with A G C C A T G T A C G T A T
C G G T A C A T G C A T A

14. Chargaff’s Rule 1950 – Erwin Chargaff discovered:
A approximately equals T
G approximately equals C
This is true for all species!
In humans
A = 30.9% and T = 29.4%
G = 19.9% and C = 19.8%

15. Let’s Put the Structure Together
Notice the following:
5’ and 3’ ends
A:T and G:C
Hydrogen bond numbers
Sugar-phosphate backbone
Two strands are antiparallel