miniPCR bio
TM
Dye Electrophoresis Lab: Molecular Rainbow - Instructor's and Student's Guide
Version: 1.0 - Release: April 2022 - © 2022 by miniPCR bio™
Student's Guide
P./9
Background information
Introduction to gel electrophoresis
-
One of the most common methods for separating and observing biological molecules in the lab
is called gel electrophoresis. The word electrophoresis means carried by electricity. During gel
electrophoresis, an electric field causes molecules with an electric charge to move through a gel.
To perform gel electrophoresis you need (1) a gel, usually made of a substance called agarose, and
(2) a way to conduct electricity through the gel.
The gel is covered in a liquid called electrophoresis buffer, which helps conduct electricity between
the two electrodes and through the gel. When the power is turned on, any charged molecules will
move through the gel towards the electrode of the opposite charge.
- - - - Negative - - - -
+ + + + Positive + + + +
Gel
Wells
Electrodes
1
Agarose gels feel
like firm Jell-O. At
the microscopic
level, the inside of
a gel looks like a
web or a sponge.
Small molecules
can move through the holes
without much trouble, but larger
molecules get slowed down. This
allows us to separate molecules
of different sizes.
2
When we make a gel, we make it
with small pockets called wells.
These wells are arranged in a line
across the gel. The wells allow us
to add our samples into the gel.
3
Metal bars or wires are placed on either
side of the gel. These act as positive and
negative electrodes. If there is a conductive
material between the electrodes, then
electrical current can flow between them.
During gel electrophoresis, charged
molecules will move through the gel
towards the oppositely charged electrode.
