Final answer:
Gel electrophoresis is a technique used to separate DNA fragments of different sizes. Agarose gel is used as the medium for the separation. The DNA fragments move towards the positive electrode based on their size and the gel is stained to visualize the separated DNA fragments.
Step-by-step explanation:
Gel electrophoresis is a technique used to separate DNA fragments of different sizes. Usually, the gel is made of a chemical called agarose. Agarose powder is added to a buffer and heated. After cooling, the gel solution is poured into a casting tray. Once the gel has solidified, the DNA is loaded on the gel and electric current is applied. The DNA has a net negative charge and moves from the negative electrode toward the positive electrode.
The electric current is applied for sufficient time to let the DNA separate according to size; the smallest fragments will be farthest from the well (where the DNA was loaded), and the heavier molecular weight fragments will be closest to the well. Once the DNA is separated, the gel is stained with a DNA-specific dye for viewing it (Figure 14.9).