Final answer:
Gel electrophoresis is a method for separating DNA fragments based on size by using an electric field, with DNA visualized post-separation using fluorescent dyes.
Step-by-step explanation:
Gel electrophoresis is an analytical technique used to separate DNA fragments by size. This is achieved by forcing the negatively charged molecules to move through a gel matrix when an electric field is applied. The DNA migrates from the negative electrode towards the positive electrode, with the rate being inversely proportional to the size of the molecules—smaller molecules travel faster and farther than larger ones.
After separation, fluorescent dyes such as ethidium bromide are used to visualize DNA fragments, appearing as distinct bands on the gel. The size of these DNA fragments can be compared to known standards called DNA ladders. Agarose gel electrophoresis is particularly common for separating nucleic acids and uses a gel made from agarose, a substance extracted from seaweed.
The pore size of the gel can vary depending on the concentration of agarose used, influencing the resolution of DNA fragment separation. Gel electrophoresis is essential in molecular biology for analyzing DNA following restriction enzyme digestion, polymerase chain reaction (PCR), or other DNA modification techniques.