Which technique is commonly used to visualize nucleic acids on gels?

Ethidium bromide staining is a technique specifically used for visualizing nucleic acids, such as DNA and RNA, that have been separated by gel electrophoresis. When nucleic acids are subjected to gel electrophoresis, they migrate through a gel matrix according to their size. After the electrophoresis process is completed, the gel is often treated with ethidium bromide, a fluorescent intercalating agent that binds to the nucleic acids.

When exposed to ultraviolet (UV) light, the ethidium bromide emits an orange fluorescence, allowing researchers to visualize the bands representing nucleic acids on the gel. This is crucial for analyzing results, as it allows for the determination of the size and quantity of the nucleic acids present.

Other techniques listed, while related to molecular biology, serve different purposes. Gel electrophoresis itself is the method used to separate nucleic acids; Western blotting is used for protein detection. The polymerase chain reaction (PCR) is a technique for amplifying specific DNA sequences, rather than visualizing them directly. Thus, ethidium bromide staining is integral to the visualization process following gel electrophoresis and is commonly used in laboratories for this reason.