Summary
An electric field separates DNA fragments by size through an agarose gel, smaller ones travelling further.
In depth
DNA is negative and moves toward the anode; smaller fragments go faster through the agarose mesh. Staining with ethidium bromide or safer dyes visualises bands against a ladder of known sizes. Proteins use SDS-PAGE.
Migration distance is inversely related to the logarithm of fragment size. Pulsed-field electrophoresis separates huge fragments. Dye front shows progress; loading buffer adds density.
Example: comparing digest bands shows plasmid size.
Gel electrophoresis separates molecules by size using an electric field. DNA is negatively charged because of its phosphate backbone, so it migrates toward the positive electrode through an agarose gel mesh, with smaller fragments moving faster and farther.
Samples are loaded into wells with dye; a DNA ladder of known sizes lets fragments be sized. Stains such as ethidium bromide or safer dyes reveal bands under UV or blue light. Proteins are separated by SDS-PAGE in polyacrylamide gels.
Example: checking whether a PCR product is the expected size.
Remember: the gel separates by size, not by sequence, and larger fragments lag behind.
Frequently asked questions
What is Gel Electrophoresis?
An electric field separates DNA fragments by size through an agarose gel, smaller ones travelling further.
Which area of biology covers Gel Electrophoresis, and how advanced is it?
Gel Electrophoresis is one of the 56 topics in Biotechnology & Genomics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Southern, Northern and Western Blots, Gene Cloning Workflow, Reporter Genes.
Can you give an example of Gel Electrophoresis?
DNA fingerprints are compared on gels.
What should I learn before Gel Electrophoresis?
Work through the Beginner topics in Biotechnology & Genomics first, such as Biotechnology, Genetic Engineering, Selective Breeding, then return to Gel Electrophoresis. Intermediate topics assume the Beginner vocabulary.
What topics are related to Gel Electrophoresis?
The closest topics to Gel Electrophoresis are Southern, Northern and Western Blots, Gene Cloning Workflow, Reporter Genes, DNA Ligase. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Gel Electrophoresis?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Gel Electrophoresis. To practise the whole of Biotechnology & Genomics, use the Biotechnology & Genomics quiz.
How is Gel Electrophoresis different from Southern, Northern and Western Blots?
Gel Electrophoresis: An electric field separates DNA fragments by size through an agarose gel, smaller ones travelling further. Southern, Northern and Western Blots: Techniques detecting specific DNA, RNA or proteins after separation and transfer to a membrane. Read both side by side and note what each one explains.
How should I study Gel Electrophoresis step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Southern, Northern and Western Blots and explain the difference aloud. Finally, take the Biotechnology & Genomics quiz and come back to this page for any question you miss.