1. - DNA as genetic material - Structure of DNA - DNA replication
Sections 8.1, 8.2, and 8.3

2. What is this stuff?

3. Deoxyribonucleic Acid Consists of 4 bases
DNA!!!
Deoxyribonucleic Acid
Consists of 4 bases
Adenine
Thymine
Guanine
Cytosine

4. Did experiments with 2 different types of pneumonia
Frederick Griffith
Did experiments with 2 different types of pneumonia
Smooth vs. rough
Smooth covered in with sugars
Rough does not have this covering

5. His experiment

6. Called the mystery material “transforming principle”
Why did this happen?
Some sort of material must have transferred between the live R and the heat killed S
Did not know it was DNA just yet
Called the mystery material “transforming principle”

7. Combined lived R bacteria with extract from S bacteria
Oswald Avery
Worked on extending Griffiths work
10 years!!!
Combined lived R bacteria with extract from S bacteria
Were able to directly observe the change of R bacteria into S

8. Avery’s experiments Qualitative tests Chemical analysis Enzyme tests
Chemical tests showed there was actually NO proteins present. Only DNA
Chemical analysis
These show the amounts or proportions of elements found in DNA. Proteins hardly contain phosphorus
Enzyme tests
Enzymes known to break down proteins and RNA did nothing to stop the transformation. Only enzymes that broke down DNA stopped the process

9. Confirmed DNA as genetic material in 1952
Hershey and Chase
Confirmed DNA as genetic material in 1952
Studied viruses that infected bacteria
Bacteriophages
Take over a bacterial cell to make more bacteriophages
Very simple things
A small amount of DNA covered by a protein coat

10. Bacteriophages!!!

11. How do they work?

12. Proteins WERE NOT passed to the bacteria from the bacteriophages
Their experiments
Experiment 1
Tagged radioactive sulfur atoms on phage’s protein molecules
Let phages infect bacteria
Studied bacteria after they were infected
Found very little radioactivity present in bacteria
Proteins WERE NOT passed to the bacteria from the bacteriophages

13. Their experiments Experiment 2
Tagged phosphorus molecules in the phage’s DNA with radioactivity
Let phages infect bacteria
Studied bacteria after they were infected
Found A LOT of radioactivity within the bacteria
DNA was passed to bacteria. More phages are made within the bacteria.
Increased phages = increased radioactive tags

14. 2 parts to the “backbone” 1 phosphate group Ring-ring shaped sugar
DNA structure
Consists of 4 bases or nucleotides
2 parts to the “backbone”
1 phosphate group
Ring-ring shaped sugar
deoxyribose

15. Adenine always pairs with Thymine
Base pairing rules
Adenine always pairs with Thymine
Double ring with double ring
Guanine always pairs with Cytosine
Single ring with single ring
A=T and C=G
Chargaff’s rule

16. Base pairing practice
GTA
CTTGAC
GATTACA
TTGGACCGGAT

17. Got credit for the shape of DNA
Watson and Crick
Got credit for the shape of DNA
Used an image they were not supposed to have
Stolen from Rosalind Franklin
They waited until she died before submitting their results to be published
Ended up winning the Nobel Prize
She got no posthumous credit for “their” work

19. Split into 2 groups