Gel Electrophoresis: One Step At a Time

Gel electrophoresis is a laboratory technique used to separate and analyze biological molecules, primarily nucleic acids (such as DNA and RNA) and proteins, based on their size and charge. It involves placing the molecules in a gel matrix and subjecting them to an electric field, causing them to migrate through the gel at different rates depending on their characteristics.

The most commonly used gels are agarose and polyacrylamide gels. For our project, we used agarose gel, which is commonly used for separating large DNA fragments, while polyacrylamide gels are used for smaller DNA fragments and proteins. The gel is prepared in a mold with wells where samples will be loaded.

The biological sample (mixed with a tracking dye) is loaded into the wells of the gel. The tracking dye allows you to monitor the progress of the electrophoresis and ensure that the sample doesn't run off the gel.

Once the samples are loaded, an electric field is applied across the gel by connecting it to a power supply. The negatively charged molecules (DNA and RNA) will migrate towards the positive electrode (anode), while the positively charged molecules will migrate towards the negative electrode (cathode).

As the molecules migrate through the gel, their movement is impeded by the gel matrix. Smaller molecules can move through the matrix more easily and thus migrate faster, while larger molecules move more slowly. This separation by size leads to the molecules forming distinct bands in the gel.

After the electrophoresis is complete, the gel is typically stained with a dye to make the separated bands visible under UV light. The resulting pattern of bands is called an electrophoretic pattern or gel image.