Chapter 7 Guided Reading Protein Function and Evolution Section 7 1 Binding a Specific Target Antibody Structure and Function 1 What are antibodies Large proteins produced by the immune system in a multitude of amino acid sequence variation to help defend the body against harmful pathogens such as bacteria viruses and other foreign substances Each variant binds with exquisite specifically and essentially non reversibly to a unique target 2 What are antibodies also called Also called immunoglobulins 3 What does our primary defense against infectious disease depend upon Depend on the ability if immunoglobulins to recognize and bind to foreign molecules Section 7 2 The Adaptive Immune Response 4 What 2 immune response mechanisms are components of the adaptive immune response Adaptive immune response Includes humoral and cellular components 5 Briefly describe these 2 immune responses The humoral immune response involves the production of specific immunoglobulin antibody molecules by B lymphocytes These antibodies are secreted and bind to invading substances making them for destruction In the cellular immune response T lymphocytes recognize and destroy foreign cells 6 Define the terms antigen and antibody Antigen The substance that elicits an immune response a toxin or other foreign substance which induces an immune response in the body especially the production of antibodies Antibody Attacks the antigen Specific immunoglobulin that binds to this Antigen 7 What is an antigenic determinant Also known as epitope is a specific molecular shape or region on the surface of an antigen that is recognized and bound by antibodies 8 What are some examples of antigenic determinants Examples of antigenic determinants epitope include groups of sugar residues in a carbohydrate or groups of amino acids on a protein surface 9 What does it mean for the adaptive immune response to have memory After there has been an initial exposure to a given antigen when a second exposure at a later date will result in a rapid and more massive production of the antigen specific antibodies 10 Where does the generation of antibodies begin The generation of antibodies begins in the bone marrow where immature B lymphocytes are produced B cells B lymphocytes are a type of white blood cell that plays a fundamental role in the adaptive immune system B cells are an essential part of the body s defense against pathogens like bacteria viruses and other foreign invaders Produce antibodies known as immunoglobulins When a B cell encounters its specific antigen it can become activated 11 What is the primary immune response The primary immune response is the initial immune response when an antigen is encountered for the first time It leads to the production of specific antibodies against the antigen T helper cells stimulates the cell carrying it to replicate and produce soluble antibodies that can circulate freely 12 What are Effector B cells Is a class of B cells and are produced in the primary response Also known as plasma cells produce soluble antibodies They lack a hydrophobic tail that binds the surface antibodies to the lymphocyte membrane 13 What are memory cells Memory cells are B cells that carry membrane bound antibodies allowing a rapid and enhanced response to a second exposure to the same antigen 14 Summarize the secondary immune response The secondary immune response is a rapid and more massive production of antigen specific antibodies upon re exposure to an antigen It is a result of the memory cells formed during the primary response 15 What prevents B cells from producing antibodies to our proteins and tissues Immature B cells that produce antibodies against self are not stimulated to replicate Rather these B lymphocytes are destroyed before they can mature Thus B lymphocytes producing antibodies against all of the potential self antigens are eliminated before release into circulation 16 Which B lymphocytes reach maturity B lymphocytes that produce antibodies against nonself substances are the ones that reach maturity Only those that produce antibodies against foreign antigens are allowed to mature 17 Describe autoimmunity Is a condition where the immune system mistakenly targets and attacks the body s own cells and tissues as if they were foreign invaders it is characterized by the loss of self tolerance 18 What are some examples of autoimmune diseases Examples of autoimmune diseases include lupus erythematosus rheumatoid arthritis multiple sclerosis type 1 diabetes mellitus psoriasis Section 7 3 The Structure of Antibodies 19 What are the 5 classes of immunoglobulins Briefly describe each You will want to know these well enough to choose the correct class given a description of the function or the shape IgM The first antibody produced in response to an antigen often in the primary immune response IgG The most abundant antibody in the bloodstream providing long lasting immunity IgA Found in secretions like saliva tears and breast milk protecting mucosal surfaces IgE Involved in allergic reactions and defense against parasitic infections IgD Functions in the activation of B cells 20 Sketch the general structure of an antibody Make sure to label the heavy and light chains as well as the antigen binding site 21 What is the difference between the constant domain and the variable domain in antibodies The constant domains of antibodies serve to hold the heavy and light chains together and function as effectors in signaling other immune cells to attack targets marked for destruction 22 Describe immunoprecipitation The figure caption for 7 1 a will be helpful Immunoprecipitation is a technique used to isolate and precipitate antigens from a mixture using antibodies It involves the binding of antibodies to antigens forming immune complexes that can be precipitated out of the solution 23 What is a requirement of the antibody for precipitation to occur For precipitation to occur in immunoprecipitation the antibody must be bivalent meaning it must have two antigen binding sites This allows the antibody to bind to multiple antigen molecules and aggregate them causing precipitation 24 What fragments are formed when an antibody is cleaved at the hinge region Give the names and brief description of each When an antibody is cleaved at the hinge region it produces two identical monovalent fragments with specific protein cleaving enzymes to produce a single fragment which has no antigen binding site and two fragments which have only