Gel Electrophoresis

Agarose Gel Electrophoresis

A laboratory technique used to separate DNA fragments based on their size by applying an electric current through an agarose gel matrix

Electrophoresis

The movement of charged molecules through a medium when an electric field is applied

Purpose of Agarose Gel Electrophoresis

To separate, visualise, and estimate the size and concentration of DNA fragments

Agarose Powder

A polysaccharide that forms a porous gel matrix allowing DNA fragments to move through it when an electric current is applied

TBE Buffer

A buffer solution that conducts electricity, maintains pH, and allows DNA to migrate through the gel

SYBR Safe

A fluorescent DNA stain that binds to DNA and allows it to be visualised under UV light

DNA Charge

DNA molecules are negatively charged and therefore migrate towards the positive electrode during electrophoresis

Loading Buffer

A solution added to DNA samples to increase density and allow visual tracking of samples during electrophoresis

Blue Loading Dye

A coloured dye used to monitor the progress of electrophoresis through the gel

Gel Wells

Indentations in the gel where DNA samples are pipetted before electrophoresis begins

Electrophoresis Tank

A chamber that holds the gel and buffer while an electric current is applied

HyperLadder

A DNA ladder containing fragments of known sizes used as a molecular size standard

Purpose of a HyperLadder

To estimate the size of DNA fragments by comparison with known band sizes

Additional Information from a HyperLadder

It can also be used to estimate DNA concentration by comparing band intensity

Voltage in Gel Electrophoresis

Electrical potential applied to drive DNA fragments through the gel (e.g. 150 V)

Run Time

The length of time electrophoresis is performed to allow adequate separation of DNA fragments

UV Light in Gel Electrophoresis

Used to visualise DNA bands because fluorescent stains emit light under UV exposure

DNA Bands

Visible lines in the gel representing DNA fragments of similar size

Smaller DNA Fragments

Move faster and travel further through the gel than larger fragments

Larger DNA Fragments

Move more slowly and remain closer to the wells

Positive Control

A sample known to contain the target DNA, used to confirm the experiment worked correctly

Negative Control

A sample that should not contain DNA, used to check for contamination

PCR Product

DNA fragments produced by polymerase chain reaction and analysed using gel electrophoresis

Base Pair (bp)

A unit used to measure the length of DNA fragments

Estimating DNA Size

Comparing the distance travelled by a DNA band to bands in the HyperLadder

Estimating DNA Concentration

Comparing the brightness of a DNA band to known concentrations in the HyperLadder