1. Separating molecules by size and charge
Gel electrophoresis
Separating molecules by size and charge
© 2016 Paul Billiet ODWS

2. Gel electrophoresis © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS

3. Electrophoresis of DNA
In electrophoresis an electric current is set up across a watery gel – agarose
Negatively charged molecules move to the positive terminal and positively charged molecules move to the negative terminal
Each nucleotide on the DNA molecule carries a negative charge
Therefore, DNA molecules only move from the negative cathode to the positive anode
© 2016 Paul Billiet ODWS

4. Electrophoresis of DNA
Negative charge increases with size, big DNA molecules move more quickly
However, bigger molecules move more slowly through the gel
The result is a steady and fine separation of DNA molecules by size
Molecules which differ by only one nucleotide in their length can be separated.
© 2016 Paul Billiet ODWS

5. Electrophoresis of DNA
Buffer solution
Agarose Gel
CATHODE -
+ ANODE
Wells for the mixture
DNA fragments separating by size
Marker molecule indicates the front
© 2016 Paul Billiet ODWS

6. Gel electrophoresis © 2016 Paul Billiet ODWS
© 2016 Paul Billiet ODWS