What is the composition of an antibody?

What is the composition of an antibody?

• A. 3 polypeptide chains
• B. 2 heavy chains and 2 light chains
• C. 1 heavy chain and 3 light chains
• D. All heavy chains

Answer: (B)

The correct answer regarding the composition of an antibody is that it consists of 2 heavy chains and 2 light chains. This structure is crucial for the antibody's function in the immune system. Antibodies, also known as immunoglobulins, are Y-shaped molecules made up of four polypeptide chains: two identical heavy chains and two identical light chains.

The heavy chains provide the basic structural framework and are responsible for the antibody's class (IgA, IgD, IgE, IgG, IgM), while the light chains assist in binding to antigens. The arrangement allows for the formation of antigen-binding sites, which are crucial for the recognition and neutralization of pathogens, such as bacteria and viruses. The specific regions of the antibody can adapt in their structure to bind to a vast array of different antigens, making the immune response highly versatile.

The correct structure enables antibodies to carry out various functions, including neutralization of toxins, opsonization, and activation of the complement system, all of which are vital for a robust immune response. Understanding this composition is fundamental to grasping how antibodies function within the larger context of the immune system.