Gel electrophoresis

Separating molecules by size and charge

Gel electrophoresis

Image credit: biotechnologyonline.gov.au/

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

© 2010 Paul Billiet ODWS

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

© 2010 Paul Billiet ODWS

Electrophoresis of DNA

Buffer solution

Agarose Gel

CATHODE -

+ ANODE

Wells for the mixture

DNA fragments separating by size

Marker molecule indicates the front

© 2010 Paul Billiet ODWS

Gel electrophoresis

Image credit: biotechnologyonline.gov.au/