2. GEL
ELECTROPHORESIS
is a laboratory
method used to
separate mixtures
of DNA, RNA, and
proteins
according to their
molecular size.
In gel electrophoresis,
the molecules to be
separated are pushed
by an electrical field
and the molecules
travel in a speed that
is inversely related to
their lengths. Smaller
molecules travel faster
than larger molecules.
3. Gel electrophoresis
involves an
electrical field
wherein one has a
positive charge
and the other has a
negative charge.
Since DNA and
RNA are negatively
charged, it will be
However, proteins
are not negatively
charged. Therefore,
researchers mix
proteins with
sodium dodecyl
sulfate to make it
unfold into linear
shape and is coated
with negative charge
4. TYPES OF GEL
ELECTROPHORE
SIS
1. HORIZONTAL GEL
ELECTROPHORESIS
The gel is cast
horizontally and
placed in a running
buffer that is
divided into two
sections with the
gel in the middle.
5. It is used for
separating DNA
and RNA
molecules.
1. VERTICAL GEL
ELECTROPHORESIS
The gel is cast
vertically. A
cathode is situated
at the top and an
anode is situated
at the bottom of
the compartment.
6. The electrode in
each compartment
provides the
required electric
field and a thin
layer of gel is
applied between
the two mounted
glass.
It is used for
7. EQUIPMENTS
USED IN GEL
ELECTROPHORE
SIS
1. GEL BOX
The gel box differs
depending the type
of gel being run.
For DNA and RNA,
a horizontal gel
box is used and
vertical gel box for
protein separation.
8. 2. GEL
can either pre-
cast or hand-cast
with wells at the
top where
samples will be
loaded. The gel is
submerged in
running buffer.
3. RUNNING BUFFER
is used to create
an electric field
that allows
movement of
molecules
through the gel
during
electrophoresis
process.
9. 5.
ELECTROPHORESIS
COMBS
These are used to
create wells in the
gel.
4. PIPETTE
are crucial tool in
gel
electrophoresis
which are used to
transfer volumes
of samples into
the wells.
10. 7. VISUALIZATION
SYSTEM
an UV light box is
used to visualize
stained DNA in
gels because it
cannot be seen by
the naked eye.
6. POWER SUPPLY
provides electrical
current through
the cables that
connects to the
positive and
negative terminals.
11. STEPS IN GEL
ELECTROPHORE
SIS
1. PREPARE THE
SAMPLE
Samples must be
processed prior to
gel
electrophoresis.
First, mix the
samples with
loading buffer
which contains
12. 2. PREPARE THE GEL
AND BUFFER
Gels can be pre-
cast or hand-cast.
In preparing the
gel there are
factors to consider
like the gel
composition,
percentage of the
Dye serves as
visual indicator
and glycerol
increases the
density of the
samples which
promotes sinking
to the bottom of
the wells
preventing it from
13. 3. LOAD AND PIPETTE
THE SAMPLES
Before loading the
samples, decide on
the ideal order of
the samples on the
gel. Using a
pipette, carefully
add the samples to
individual wells.
Running buffer can
often be
purchased. When
you’re ready to
load, remove the
comb from the gel,
fill the gel box with
buffer and place it
into the chamber.
The box should be
14. 3. ELECTROPHORESIS
(RUN THE GEL)
Once the samples
are loaded, the lid
is placed on the
gel box, the cords
are connected to
the power supply
and the gel is run
with
Additionally, a
ladder with specific
size markers is
added to one of
the wells as a
reference for
downstream
analysis.
15. a. The degree
separation
required
b. The voltage
applied
c. The gel’s
composition
The voltage and
time required is
adjusted based on
each laboratory’s
specific
experiment. The
run time can vary
anywhere from 45-
90 minutes
depending the
16. Ethidium bromide
intercalates
between DNA and
is visible under UV
light and this is
sometimes added
directly to the
agarose gel. The
stained gel is then
exposed to UV
5. VISUALIZE AND
DOCUMENT BANDS
Once the dyed
samples have
migrated through
the gel far enough,
the power supply
is turned off and
the gel is removed
and placed into an
17. DNA bands are
visualized from
each lane
corresponding to a
chamber well. The
DNA ladder that
was loaded is also
visualized and the
length of the DNA
bands can be
VIDEO PRESENTATION OF
HORIZONTAL GEL
ELECTROPHORESIS
