Question
Glycoprotein molecule shown in Photograph is produced by ?
A. B-cells.
B. T-cells.
C. Macrophages.
D. NK cells.
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Correct Answer » A Explanation |
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Ans:A. B cells.
The image shown is of immunoglobulin.
Glycoprotein molecule in an immunoglobulin is produced by B-cells.
Immunoglobulins are glycoprotein molecules that are produced by plasma cells( differentiated B cells ) in response to an immunogen and which function as antibodies.
BASIC STRUCTURE OF IMMUNOGLOBULINS
A.) Heavy and Light Chains
- All immunoglobulins have a four chain structure as their basic unit. They are composed of two identical light chains and two identical heavy chains .
B.) Disulfide bonds
- Inter-chain disulfide bonds – The heavy and light chains and the two heavy chains are held together by inter-chain disulfide bonds and by non-covalent interactions .
- Intra-chain disulfide binds – Within each of the polypeptide chains there are also intra-chain disulfide bonds.
C.) Variable (V) and Constant (C) Regions
- Heavy and light chain could be divided into Variable and Constant regions based on variability in the amino acid sequences.
D.) Hinge Region
- This is the region at which the arms of the antibody molecule forms a Y.
E.) Domains
- Three dimensional images of the immunoglobulin molecule show that it is not straight.
- Rather, it is folded into globular regions each of which contains an intra-chain disulfide bond .These regions are called domains.
F.)Fab ,F c and Paratope region
- Fab region:The arms of the Y contain the sites that can bind to antigens.This region of the antibody is called the Fab (fragment, antigen-binding) region. It is composed of one constant and one variable domain from each heavy and light chain of the Antibody.Fab region of the antibody determines antigen specificity
- Fc region:The base of the Y plays a role in modulating immune cell activity. This region is called the Fc (Fragment, crystallizable) region, and is composed of two heavy chains that contribute two or three constant domains depending on the class of the antibody.Fc region of the antibody determines the antibody’s class effect.
- Paratope:Antigen binding site.
