1. Set up Cornell Notes on pg. 67
8.2 Structure of DNA
2.1 Atoms, Ions, and Molecules
Set up Cornell Notes on pg. 67
Topic: 8.2 Structure of DNA
Essential Question:
Explain the base-pairing rules. How many types of nucleotides are there? How do they differ?
Don’t forget to add it to your T.O.Contents!
Explain the base-pairing rules. How many types of nucleotides are there? How do they differ?
Key Concept:DNA structure is the same in all organisms

2. KEY CONCEPT DNA structure is the same in all organisms.

3. DNA is composed of four types of nucleotides.
Each nucleotide has three parts.
1. a phosphate group
2. a deoxyribose sugar
3. a nitrogen-containing base
base
phosphate group
deoxyribose (sugar)
nitrogen-containing
base 1 3 2
backbone
Covalent bonds

4. Thymine- T Adenine- A Guanine- G Cytosine-C
The nitrogen containing bases are the only difference in the four nucleotides.
BASES
Thymine- T
Adenine- A
Guanine- G
Cytosine-C

6. Watson and Crick determined the three-dimensional structure of DNA by building models.
They realized that DNA is a double helix
backbone on the outside
bases on the inside.
bases
backbone

7. Watson and Crick’s discovery built on the work of Rosalind Franklin and Erwin Chargaff.
Franklin’s x-ray images suggested that DNA was a double helix of even width.
Chargaff’s rules stated that A=T and C=G.

8. Nucleotides always pair in the same way.
A pairs with T
C pairs with G
the helix has a uniform width.
Ex: ladder C G T A

9. The backbone is connected by covalent bonds.
The bases are connected by hydrogen bonds.
Hydrogen bond
hydrogen bond
covalent bond
backbone
Bases (A,T,G,C)

10. A T C G G C T A T A G C

11. GATTACAATCGATCGAT CTAATGTTAGCTAGCTA TAGGACTACTAGTCGTA
Using the base pairing rules- complete the DNA strand:
GATTACAATCGATCGAT
CTAATGTTAGCTAGCTA
TAGGACTACTAGTCGTA
ATCCTGATGATCAGCAT

12. Have Your DNA & Eat It Too
Adenine (A) = Green
Thymine (T) = Pink
Cytosine (C) = Yellow
Guanine (G) = Orange
* I need to check your work before you eat the DNA!!!!!