Transcript DNA and RNA - Animo Venice Biology

DNA
The Blueprints for Life
January 22th, 2009
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
Nucleotide Structure
Phosphate Group
Nitrogenous Base
5-Carbon
Sugar
• 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.
• Cytosine and Thymine belong to a group
of compounds know as pyrimidines, which
contain one ring in their structures.
• 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.
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.