_______ _______ is a technique used to detect a particular sequence in a sample of DNA.

Southern blotting is a technique specifically designed to detect a particular sequence of DNA within a sample. The process involves the separation of DNA fragments through gel electrophoresis, followed by the transfer of those fragments to a membrane. Once on the membrane, the DNA is hybridized with a labeled probe that is complementary to the target sequence. If the target sequence is present in the sample, the probe will bind to it, allowing for visualization, typically using methods such as autoradiography or fluorescence.

This technique is crucial in various molecular biology applications, such as gene cloning, gene mapping, and the study of DNA rearrangements. It allows for both qualitative and quantitative analysis of specific DNA sequences, making it a powerful tool in genetics and genomics.

Other techniques mentioned in the choices serve different purposes; for example, Western blotting is used to detect proteins, Northern blotting is for RNA detection, and gel electrophoresis is a method for separating nucleic acids or proteins based on size but does not inherently provide information about specific sequences.