Final answer:
In a Western Blot, the 2nd antibody is used to bind to the 1st antibody. It is equipped with a molecular beacon that recognizes and binds to the 1st antibody. The 2nd antibody is usually coupled to an enzyme or a fluorophore for detection.
Step-by-step explanation:
The 2nd antibody in a Western Blot is used to bind to the 1st antibody. The 1st antibody is produced to specifically bind to the protein of interest, while the 2nd antibody is equipped with a molecular beacon that recognizes and binds to the 1st antibody. The 2nd antibody is usually coupled to an enzyme or a fluorophore, which allows for detection and visualization of the protein of interest.