- Gel electrophoresis is a technique used to separate DNA fragments according to their size.
- DNA samples are loaded into wells (indentations) at one end of a gel, and an electric current is applied to pull them through the gel.
- DNA fragments are negatively charged, so they move towards the positive electrode. Because all DNA fragments have the same amount of charge per mass, small fragments move through the gel faster than large ones.
- When a gel is stained with a DNA-binding dye, the DNA fragments can be seen as bands, each representing a group of same-sized DNA fragments.
What is a gel?
How do DNA fragments move through the gel?
Visualizing the DNA fragments
Check your understanding
This lane contains the longest DNA fragment.
This lane contains the shortest DNA fragment.
This lane contains a base pair (bp) DNA fragment.