Immunology Unit 1 - 1 Immunology Unit 1 Study Guide...

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1 Immunology Unit 1 Study Guide Terminology: antigens (Ag) substances which elicit an immune response immune system of vertebrates is designed to recognize foreign elements in the host-organism any foreign intruder that elicits an immune response is called an antigen any foreign molecule that will stimulate antibody (Ab) any substance that can bind to specific antibody molecule or specific antigen receptors on lymphocytes antigenic determinant the part of the antigen to which the antibodies bind epitope same as the antigenic determinant may be a polypeptide structure, a carbohydrate or a simpler group attached to the antigen polypeptide epitopes – divided into 2 types depending on their structure – usually about 5 (4-6) amino acid residues in length continuous epitope all amino acids making up the epitope in a continuous stretch of residues in the sequence of the antigen discontinuous epitope the recognized residues are clustered in space but distant in primary structure a distinct site ( epitope ) on the antigen can react with an antigen binding site ( paratope ) on the antibody immunogen – an antigen that stimulates production of antibodies that bind to it haptens – small molecules that are not antigenic themselves – can attach to proteins in the body to become antigenic an incomplete antigen (hapten) is a chemically defined substance of low molecular weight that can not induce an adaptive immune response by itself can react with the paratope on an antibody can produce antibodies if they are conjugated to a larger carrier molecule (normally a protein) types of antigens: soluble and cell-bound proteins constitute the largest group of naturally occurring antigens in addition polysaccharides, lipids and nucleic acids (often associated with proteins) are also antigenic large antigens can possess many different epitopes on the same molecule the paratope (antigen binding site) is concave pocket that matches the convexity of the epitope the paratope and epitope must come in close contact with each other since the binding forces are weak some parts of the epitope are more immunodominant than others the immunodominant subunit is usually the terminal residue of the sequence when the epitope is a terminal sequence some amino acids contribute to the epitope more than others antibodies bind to antigen by noncovalent binding thru charged groups and hydrophobic groups – amino acids like lysine and glutamic acid, alanine, leucine, tyrosine, phenylalanine, and valine are important to the formation of the epitope Antibodies – Basic Structure: antibodies (immunoglobulins – Ig) are proteins one end of the Ig binds to antigens (Fab portion because it is the fragment of the molecule which is antigen binding) and the other end is crystallizable and called Fc – responsible for effector functions:
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2 5 classes of Ig
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This note was uploaded on 04/07/2008 for the course IMMUNOLOGY 101 taught by Professor Vicious during the Spring '08 term at Palmer Chiropractic.

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Immunology Unit 1 - 1 Immunology Unit 1 Study Guide...

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