1. DNA The Blueprints for Life
January 22th, 2009

2. What is DNA?
DNA stands for deoxyribonucleic acid. It is a macromolecule made up of monomers called nucleotides. Each nucleotide is made up of three basic components:
a 5-carbon sugar called deoxyribose
a phosphate group
and a nitrogenous (nitrogen-containing) base

3. Nucleotide Structure
5-Carbon
Sugar
Phosphate Group
Nitrogenous Base

4. There are four different nucleotides found in DNA.
Adenine and Guanine belong to a group of compounds know as purines, which contain two rings in their structures.

5. Cytosine and Thymine belong to a group of compounds know as pyrimidines, which contain one ring in their structures.

6. The phosphate and sugar make up the back bone of the helix.
The four nitrogenous bases pair up to form a long, double-stranded helix of DNA.
Adenine (A) always pairs with Thymine (T)
Cytosine (C) always pairs with Guanine (G)
The phosphate and sugar make up the back bone of the helix.

7. The Double Helix Phosphodiester bond Hydrogen bond
The phosphate and sugar backbone of the helix are held together by strong covalent phosophodiester bonds.
The base pairs that make up the middle of the helix are held together by weak hydrogen bonds.