1. Objective: What is the structure of DNA?
Do Now: Take out your HW and notes 4

2. Watson and Crick Modeled DNA’s structure.
Using Franklin’s work, created a new model in which two strands of nucleotides wound about each other, forming a double helix

3. Chargaff’s rules state that in any species there is an equal number of A and T bases, and an equal number of G and C bases

4. DNA (deoxyribonucleic acid)
The heritable genetic information of an organism

5. Write down on your note sheet the importance of Watson and Crick.

6. What does DNA look like?
Double Helix: structure of DNA – 2 strands, twisted into a helical shape
Make an analogy for the structure of DNA.

7. Nucleotides Subunits (monomers) of DNA (polymer) Made up of: Sugar
Phosphate group
Nitrogenous Base

8. Nucleotides join together
Joined together by covalent bonds that connect sugar of one nucleotide to the phosphate group of the next
The repeating pattern of sugar-phosphate is called a sugar-phosphate “backbone”

9. Base-Pair Rule
DNA is made up of 4 nitrogenous bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C)

10. The Base Pairing Rule (A) Adenine = (T) Thymine
(C) Cytosine = (G) Guanine
Bases joined together by hydrogen bonds

11. Fig. 16-UN1
Purine + purine: too wide
Pyrimidine + pyrimidine: too narrow
Purine + pyrimidine: width consistent with X-ray data

12. Fig. 16-8 Adenine (A) Thymine (T) Guanine (G) Cytosine (C)
Figure 16.8 Base pairing in DNA
Guanine (G)
Cytosine (C)

13. Practice
One DNA strand is provided, write the bases of the complimentary strand C G T A G C A T

14. Activity- Making a Model of DNA
Materials:
4 beads of different color
2 long pipe cleaners
8-12 short pieces of pipe cleaner
1 index card
1 DNA sequence