Electrophoresis
Electrophoresis is a technique used to separate DNA fragments based on their size by applying an electric field.
Key Principle
- Charged molecules, like DNA, move when exposed to an electric field.
- DNA is negatively charged due to its phosphate backbone and migrates towards the positively charged electrode (anode).
Method Overview
- DNA samples are loaded into wells within a gel matrix, often made of agarose.
- An electric current is passed through the gel.
- Smaller DNA fragments move more quickly through the gel, while larger fragments move more slowly, allowing for size-based separation.
Visualizing the Results
- After the run is complete, the gel is stained with a fluorescent dye(Ethidium bromide) that binds to DNA.
- Under ultraviolet light, the DNA fragments appear as bright bands.
- The position and intensity of these bands can be compared to molecular weight markers to assess fragment size and concentration.
Use in PCR Analysis
- Electrophoresis is commonly used to verify the success of a PCR reaction.
- Following PCR, the product is run on a gel. If amplification was successful, a visible band will appear at the expected size.