1. Today’s Objectives: DNA Structure Notes DNA Song Finish Race to DNA
Happy Friday!
Today’s Objectives:
DNA Structure Notes
DNA Song
Finish Race to DNA
Practice Page

2. DNA
Structure

3. DNA Scientists Watson and Crick (1950s) Credited with discovering DNA
Rosalind Franklin (1950s)
Helped discover the structure of DNA
Wilkins (1950s)
Took X-ray pictures of DNA
Chargoff (1940s)
Determined base pairing rules

4. DNA Structure
DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of tiny subunits called Nucleotides.
Each nucleotide consists of:
phosphate group
5-carbon sugar (DNA = deoxyribose)
nitrogenous base

5. Nucleotide (Draw on the back of your paper!) Nitrogenous Base 5-carbon
Phosphate
Nitrogenous
Base
5-carbon
Sugar
(Draw on the back of your paper!)

6. Nucleotides
The phosphate and sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”.
There are four types of nitrogenous bases.

7. Nucleotides: Nitrogen Bases
Adenine T
Thymine C
Cytosine G
Guanine

8. Pyrimidines have a “y” in their name!
Nitrogen Bases
Two Types:
Purines: Double ring structure
Adenine
Guanine
Pyrimidines: Single ring structure (like a pie)
Thymine
Cytosine
Pyrimidines have a “y” in their name!

9. Scientist responsible for complimentary base pair rules:
Nucleotides
Each base will only bond with one other specific base.
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
Scientist responsible for complimentary base pair rules:
Erwin Chargaff
base pair
base pair

10. C+G = Cows and Goats OR CoverGirl
How can we remember??
A+T = At
C+G = Cows and Goats OR CoverGirl

13. DNA Structure
Because of this complementary base pairing, the order of the bases in one strand determines the order of the bases in the other strand.

14. A C T G G A T C

15. Bonds in DNA
Hydrogen Bonds: hold nitrogen bases together (in the middle)
Covalent Bonds: hold sugar from one nucleotide to phosphate of a neighboring nucleotide (on the edges)

16. Bonds in DNA
Hydrogen Bonds
Covalent Bonds