1. DNA History and DNA Structure

2. How did we get here?? – Make a table using pages 204-212
Name
Discovery
Importance
Frederick Griffith
Oswald Averey, Colin MacLeod and Caclyn McCarty
Hershy and Chase
Chargaff
Levene
Rolalind Franklin
Watson and Crick

3. DNA structure
Purines have two rings
Pyrimidines have one ring

4. DNA has four kinds of bases, A, T, C, and G
Thymine (T)
Cytosine (C)
Adenine (A)
Guanine (G)
Pyrimidines
Purines
Figure 10.2B

5. DNA is a double-stranded helix
James Watson and Francis Crick worked out the three-dimensional structure of DNA, based on work by Rosalind Franklin
Figure 10.3A, B

6. Sugar-phosphate backbone
DNA and RNA are polymers of nucleotides
DNA is a nucleic acid, made of long chains of nucleotides
Phosphate group
Nitrogenous base
Nitrogenous base (A, G, C, or T)
Sugar
Phosphate group
Nucleotide
Thymine (T)
Sugar (deoxyribose)
DNA nucleotide
Polynucleotide
Sugar-phosphate backbone
Figure 10.2A

7. Partial chemical structure
Hydrogen bonds between bases hold the strands together: A and T, C and G
Hydrogen bond
Ribbon model
Partial chemical structure
Computer model
Figure 10.3D

8. Each strand of the double helix is oriented in the opposite direction
5 end
3 end P P P P P P P P
3 end
5 end
Figure 10.5B

9. DNA structure
Figure ’ end : Phosphate at carbon 5 is not bound to another nucleotide
3’ end – carbon at position 3 is not joined to another nucleotide.

10. DNA structure What is the complementary sequence to the following ?
5’ – ATG – 3’
Draw the complementary sequence.
Include all the correct drawing of molecules, and the bonding between them. Consult your text book for help.
Read pages

11. DNA structure Packing of information 2 m of material in 4 uM
DNA associates with a family of proteins called histones
Histones form structures called nucleosomes
Condense further to ultimately form chromatin –
Long intertwined strands of DNA.
During cell division threads of chromatin condense and become visible as distinct chromosomes

12. DNA structure DNA super coiling:
the formation of additional coils in the structure of DNA due to twisting forces on the molecules

13. What is a chromatid? What is a centromere? What is a chromomere?
Chromatid - one of the two copies of DNA making up a duplicated chromosome, which are joined at their centromeres.
Centromere – a protein structure that links sister chromatids
Chromomere - serially aligned beads or granules of eukaryotic chromosome resulting from local coiling.

15. Name
Discovery
Importance
Frederick Griffith
Passing information from one cell to another
Cells can store information – the “transforming principle”
Oswald Averey, Colin MacLeod and Caclyn McCarty
DNA is where information is stored
Targeting the molecules of heredity
Hershy and Chase
Confirmed that DNA was the molecule of interest
Focused scientists on DNA
Chargaff
Nucleotides are present in certain proportions (A=T, C+G)
Provided insight for solving the structure of DNA.
Levene
Isolated and named nucleic acids
Rolalind Franklin
The structure of DNA
Provides a framework for solving the structure
Watson and Crick
Build the model
Had properties consistent with ‘the molecular code for life”