Download DNA structure and function

DNA:
Structure
DNA Structure and Purpose
• In simplest terms, DNA is a blueprint for life.
• It is made up of genes which hold the information
for making proteins within the cell
– Proteins in turn help make up everything in your body!
• DNA is a very long polymer made up of monomers
called nucleotides
• The basic 3D shape of DNA is called the double
helix
• The double helix looks like a twisted ladder or
zipper.
DNA’s
Structure
C
G
A
T
How is DNA held together??
• The nitrogen bases
are connected by
Hydrogen bonds
• The backbone
(sides) are
connected by
Covalent bonds.
Nucleotide
Hydrogen
bonds
Sugar-phosphate
backbone
Covalent
bonds
1 monomer!!! Aka
nucleotide
8 monomers
making a small
section of DNA
Nitrogen
base
Deoxyribose
Phosphate
• Sides of DNA are always
made up of a Phosphate and 5
carbon sugar (deoxyribose).
• Middle or rungs of DNA are
always made up of 4 different
nitrogen base pairs.
Covalent bonds
Hydrogen bonds
Nitrogenous Bases
1. PYRIMIDINE
– 1 ring
– Pyrimidines have “y”
**Remember:
*Cytosine (C)
*ThYmine (T)
2. PURINE
– 2 rings
– Adenine (A)
– Guanine (G)
**Remember: “PUGA2”
Nitrogen Base pairing
• One pyrimidine
and one purine
will ALWAYS
pair up.
• A pairs with T
• G pairs with C
Location and Form of DNA
• Prokaryotic DNA is located in the
cytoplasm, usually in a circular form
• Eukaryotic DNA is located inside the
nucleus in the form of chromosomes
• How does all that DNA fit into the nucleus? Hopefully
you remember this picture from cell division!
Review!!!
• What does A pair with?
• What does C pair with?
• What makes up the sides
of a the DNA strand?
• What are the base pairs
held together by?
• What consists of a
phosphate group, 5carbon sugar and a
nitrogen base?