Agarose gel electrophoresis is a technique used to separate DNA fragments by size. DNA has a negative charge and will migrate toward the positive electrode in an agarose gel, allowing DNA fragments of different sizes to be separated. Key aspects of agarose gel electrophoresis include using an agarose gel made from seaweed extract, loading DNA samples into the gel wells, running a current through the gel to separate the DNA by size, and staining the gel with a dye like ethidium bromide to visualize the DNA fragments under UV light.

1. Agarose Gel Electrophoresis
M. Nawaz Shah

2. Introduction
• Using electrophoresis , we can see how many
different DNA fragments are present in
sample and how large they are relative to
one another.
• DNA fragments are negatively charged , So
they move towards the positive electrodes.

3. Agarose gel
• Agarose a linear polymer of
D-galactose and and 3,6-anhydrogalactose
• Natural polymer Extracted
from Red Algae
• Unique gelling property does
not require a cross linker.
D-galactose and 3,6-anhydrogalactose
Red Algae

4. How to make Gel?
Buffer
Water

5. DNA Fractionation Ranges with Agarose
Agarose
%Agarose in gel Ranges of resolution (Kbp)
0.3 5-60
0.6 1-20
0.7 0.8-10
0.9 0.5-7
1.2 0.4-6
1.5 0.1-3

6. Time Requirement
Time requirement for performing DNA Agarose Gel Electrophoresis (8cm)
Procedure Time Requirement
Prepare and pour the gel 45 min to 1 hr
Prepare and load DNA samples 10 min
Run the gel 45 min to overnight
Stain and photograph the gel 1 hr

7. Size of the gel
The % of agarose
Voltage
Running Buffer and staining
Strategic Planning

8. Buffer

9. Stains
• Ethidium Bromide is used to stain DNA and
RNA.
• For DNA Gels, one can choose to stain the
gel after run is complete or to include it in
the gel.
• mutagenic
Ethidium Bromide

10. Steps

11. Steps
DNA
Samples
DNA
ladder
DNA samples
are loaded
into wells.

12. Steps DNA
Samples
DNA
ladder
The electric current is turned
on.The negatively Charged DNA
moved toward the positive
electrode.
When a gel is stained
with a binding dye
and placed under UV
light. DNA fragments
will glow.
800
700
600
500
400
300
200
100
1200
900
Largest
Smallest
bp