1. Ch9: DNA
Molecular Heredity

2. Views on Genes Mendel, “genes are separate, physical entities”
Morgan, “genes are in chromosomes”
NOW, genes are chemical!
(DNA)

3. How to prove that genes are in DNA, not the histone proteins?
Use a Virus! (bacteriophage, infects bacteria)
Virus has DNA, but just a few types of protein
Infects stops bacteria function  minutes later bacteria dies  100’s viruses released
Only the virus’ DNA injected into bacteria

4. Transformation Bacteria can change genetics
Bacteria Strain A + Strain B  Bacteria Strain B
“Transgenic” create a new organism

5. Discovering DNA’s 3D Structure

6. X-Ray Crystallography

8. DNA Characteristics Double Helix
Right Handed (thumb up, follow curve towards fingers)
Antiparallel: 5’3’
2 strands move in opposite directions
Major & Minor Grooves
MAJOR: Top of Pyrimidine (CT) + Purine (AG)
MINOR: Bottom Pyrimidie +Purine
Gives zipper look 5’ 3’ 3’ 5’

10. Importance of Double Helix
HOLDS GENETIC INFO: Differences in DNA causes differences amongst species & individuals
AT/CG MATCHING NECESSARY FOR DNA REPLICATION
SUSCEPTIBLE TO MUTATIONS
When DNA is copied & turned into RNA, GENES BECOME PHENOTYPES!

11. DNA Replication