Our bodies have the capacity to make unique antibodies that can recognize billio

Question

Our bodies have the capacity to make unique antibodies that can recognize billions of foreign antigens. Yet, we don't carry billions of unique genes to make these antibodies. It would completely overburden our cells to carry that many genes. Our immune cells have developed a clever trick to randomly generate these billions of antibodies through chromosomal rearrangement. Explain how the immunoglobulin genes are rearranged to generate billions of different antibodies. HINT: Explain how the chromosome is rearranged to generate so many different variations.

Explanation / Answer

Immunoglobulins are plasma proteins which are produced during certain immune response. Antigens like bacteria, virus etc stimulate the production and activation of billions of antibodies. This antibodies disables the invading antigen.

Immunoglobulin is a Y shaped molecule. It is made up of four polypeptide chains which is of two identical "light" and "heavy" chains of amino acids connected by disulfide bond.Light chains may be kappa or lambbda. The major 5 heavy chains include IgM,IgG,IgA,IgD and IgE.Each of these differ in the location in our body and the stimulation of the innate system to disable antigen. It also contains variable region and constant region which is responsible for binding to antigen.

The immunoglobulin genes are rearranged to generate billions of different antibodies by rearranging DNA segments during B cell development, prior to antigen exposure. Mutation is one of the other reason which can also increase genetic variation in antibodies.

When Stem cells changes to B cell, the DNA segments for both heavy and light chains are randomly combined. Each and every B cells makes one light and one heavy chain which is coding for an antibody as a membrane bound receptor. Specificity to different antigen depends upon the gene fragments used. These produced antibodies canreact with allmost all natural chemical structures including our own proteins.

Over 15,000,000 variations is possible only through recombining gene fragments. Mutation also plays a major role in it to produce billions of antibodies.

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