1. DNA!
DNA
The Molecule of Life
The molecule of life

2. Griffith Experiment conducted in 1928
Virulent (infectious) and avirulent (non- infectious) strains of bacteria
Rough strain=avirulent
Smooth strain=virulent

3. From this, Griffith discovered…Bacterial Transformation

4. Avery, MacLeod and McCarty (1944)
What conclusions can be made from their results?

5. Hershey and Chase Alfred Hershey and Martha Chase - 1952
Studied bacteriophage; a virus that invades bacteria
Labeled protein with radioactive sulfur
Labeled DNA with radioactive phosphorus
What can we conclude from their results?

6. Rosalind Franklin
Rosalind Franklin was a female scientist working with DNA
Performed x-ray crystallography to reveal structure of DNA in 1952
Her data was given away without her knowledge

7. Watson & Crick
James Watson and Francis Crick used Franklin’s photographs to determine structure of DNA
1953-made model and published article about structure of DNA

8. DNA = Deoxyribonucleic Acid
Holds genetic information of cells
DNA kept in the nucleus
Forms double helix

9. Connection to Macromolecules
DNA is a nucleic acid
The monomer of a nucleic acid is a nucleotide
3 parts of a nucleotide
Nitrogenous Base
5-Carbon sugar
Phosphate group
Draw and label this in your notes!

10. Two Categories of Nitrogen Bases
Each NUCLEOTIDE is the same, except for its nitrogen base
A nitrogenous base can either be a
PYRIMIDINE or a PURINE
1 Carbon Ring
2 Carbon Rings

11. Nitrogen Bases Adenine (purine) Thymine (pyrimidine) Guanine (purine)
The 4 nitrogenous bases
found in DNA are:
Adenine (purine)
Thymine (pyrimidine)
Guanine (purine)
Cytosine (pyrimidine)

12. What bases are purines? Pyrimidines?

13. Chargaff’s Discovery
He found that the amount of adenine always equaled thymine and that the amount of guanine always equaled cytosine
However the amount of A+T often did not equal the amount of C+G
What do you think that he was able to conclude from this?

14. Complimentary base pairing
Adenine always pairs with Thymine
Cytosine always pairs with Guanine
The 2 strands are joined by weak hydrogen bonds

15. 2 chains of nucleotides bind to form a DNA molecule
Hydrogen bonds form between nitrogenous bases to join the 2 chains together
The sugar and phosphate group together is known as the sugar-phosphate backbone

16. What is the complementary base sequence on the other strand of the DNA?
A T T G C C C T A A
Template Strand
Complementary
Strand
T A A C G G G A T T

17. DNA is anti-parallel
Anti-parallel: the 2 strands run side- by-side in opposite directions AND are complimentary to each other

18. Test questions:
If a section of DNA consisted of 30 nucleotides, and 10 of them were adenine nucleotides, how many thymine, guanine, and cytosine nucleotides are there?
If the insulin gene consists of 40 base pairs, and 32 adenine nucleotides were present, how many guanine, cytosine, and thymine nucleotides are present?

19. Sugar-phosphate backbone Nitrogenous bases
The classic picture of a DNA strand. You should now be able to recognize:
Sugar-phosphate backbone
Nitrogenous bases
the 4 types
Purines and Pyrimidines
2 chains of nucleotides
Base-pairing rules