What role does the electric current play in gel electrophoresis?

In gel electrophoresis, electric current plays a critical role in facilitating the movement of DNA fragments through the gel. When a voltage is applied across the gel, it creates an electric field that interacts with the negatively charged DNA molecules. DNA naturally has a negative charge due to its phosphate backbone, which causes it to move towards the positive electrode when the current is applied.

As the DNA fragments migrate through the gel matrix, they are separated based on size; smaller fragments move faster and travel further than larger ones. This separation allows for the analysis of different DNA fragments, making it possible to visualize them after staining. Such movement is fundamental to the technique, enabling researchers to isolate and study specific DNA sequences for various applications, such as genetic analysis, forensic investigations, or cloning.