Final answer:
The secondary antibody in western blotting is derived from a different species than the primary antibody, binds to the primary antibody, and is labeled with a detection molecule. Hence, all of the above-mentioned characteristics are correct.
Step-by-step explanation:
The characteristics of a secondary antibody used in western blotting include:
- It is derived from a species different than that of the primary antibody.
- It recognizes and binds to the primary antibody.
- It is labeled with a detection molecule, such as an enzyme or fluorophore, which allows for visualization of the protein of interest after the secondary antibody binds to the primary antibody.
Therefore, the correct answer is 4) All of the above. Secondary antibodies in western blot serve the crucial role of detecting the primary antibodies that have specifically bound to target proteins. They are essential for enabling researchers to observe and measure the presence and quantity of the protein under study.