Immunology- Antigen And Antibody Structure Quiz

IgE is involved in allergic responses.

The heavy chain is the correct answer because it has both a fragment crystallizable (Fc) region and a Fab region. The Fc region is responsible for binding to immune cells, while the Fab region is responsible for binding to antigens. The heavy chain is an important component of antibodies and plays a crucial role in the immune response.

IgA is the main immunoglobulin in the gut and secretions such as saliva, milk, and tears. It plays a crucial role in mucosal immunity, which is the body's defense mechanism against pathogens at mucosal surfaces. IgA helps to prevent the attachment and entry of pathogens into the body by neutralizing them and enhancing their clearance. It is particularly important in protecting the mucosal surfaces of the respiratory, gastrointestinal, and urogenital tracts. IgD, IgE, IgG, and IgM are also immunoglobulins, but they do not have the same prevalence or function in mucosal immunity as IgA.

Gamma globulin serum fraction contains predominantly IgG immunoglobulin. This is because IgG is the most abundant immunoglobulin in the serum, comprising about 75% of the total immunoglobulin pool. IgG plays a crucial role in immune defense by neutralizing pathogens, activating complement system, and facilitating phagocytosis. It is also the only immunoglobulin that can cross the placenta, providing passive immunity to the fetus. IgA, IgD, IgE, and IgM are present in smaller amounts in the serum and have different functions in the immune system.

IgG is the correct answer because it is the only immunoglobulin that can transfer across the placenta and provide maternal protection to the fetus. IgE is involved in allergic reactions, IgM is the first antibody produced in an immune response, and IgA is primarily found in mucosal secretions. Therefore, only IgG matches the functional description given.

The Fc region is the part of an antibody that binds to various cellular receptors and to complement. The Fc region is found in the constant region of the antibody, while the Fab region is responsible for binding to antigens. The heavy and light chains make up the structure of the antibody, with the hinge region providing flexibility.

IgM is structurally characterized as pentametric because it is composed of five subunits. Each subunit consists of two heavy chains and two light chains, making a total of ten chains in the pentameric structure. This arrangement allows IgM to have a larger size compared to other immunoglobulins, and it plays a crucial role in its function as a first-line defense against pathogens. The pentameric structure also contributes to its ability to agglutinate antigens and activate the complement system efficiently.

Passive immunity is the transfer of antibodies from one individual to another, providing immediate protection against a specific pathogen. In this case, the runner was given human immunoglobulin G-containing antibodies to rabies virus, which conferred instant protection against the rabies virus without the need for the runner's body to develop a response. This is an example of passive immunity because the antibodies were transferred to the runner rather than being produced by his own immune system.

The Fab region refers to the antigen-binding fragment of an antibody. It is responsible for binding to the specific antigen. The Fab region is composed of both the light chain and heavy chain of the antibody. The light chain and heavy chain combine to form the variable region of the Fab region, which contains the antigen-binding site. The Fc region, on the other hand, is responsible for mediating effector functions of the antibody, such as binding to immune cells. The hinge region provides flexibility to the antibody molecule, allowing it to bind to antigens at different angles.

The hinge region is the correct answer because it allows for flexibility. This region connects the two heavy chains in an antibody and allows them to move independently, providing flexibility and mobility to the antibody molecule. This flexibility is important for the antibody to bind to different antigens and perform its various functions in the immune response. The hinge region acts as a pivot point, allowing the antibody to change its shape and adapt to different targets, enhancing its effectiveness in recognizing and neutralizing pathogens.

Adjuvants are agents often used to modify or augment the effects of a vaccine by stimulating the immune system to respond more vigorously. They help to enhance the immune response to the vaccine, resulting in increased immunity to a particular disease. Adjuvants can be substances such as aluminum salts, oil-based compounds, or virosomes that are added to vaccines to improve their effectiveness.

IgM is the correct answer because it is predominantly present in the primary (early) immune response. IgM is the first antibody produced by the body when it encounters a new antigen, making it important for the initial defense against infections. It is a pentameric antibody, meaning it consists of five units, and it is effective in activating complement and promoting the clearance of pathogens. IgG, IgE, IgG & IgM, and IgG & IgA are not predominantly involved in the primary immune response.

IgE binds to an Fc receptor on mast cells and basophils. This binding triggers the release of inflammatory mediators, such as histamine, which are involved in allergic reactions. IgE is primarily responsible for allergic responses and plays a crucial role in immune defense against parasites.

The antibodies (immunoglobulins) are initially found in the Gamma globulin fraction when using lytical techniques such as electrophoresis.

IgG and IgM are the correct answers because both of these immunoglobulins have the ability to activate the complement system. IgG is the most abundant immunoglobulin in the body and can activate the complement system through the classical pathway. IgM is the first antibody produced during an immune response and can activate the complement system through the classical pathway as well. IgE is involved in allergic reactions and IgA is primarily found in mucosal secretions, neither of which have a direct role in activating the complement system.

Papain is a proteolytic enzyme that specifically cleaves the hinge region of immunoglobulins. The hinge region is a flexible region that connects the heavy and light chains of the immunoglobulin molecule. Cleavage of the hinge region by papain results in the formation of two Fab fragments and one Fc fragment. This cleavage is important in various immunological techniques and applications, such as generating antibody fragments for research or therapeutic purposes.

Pepsin is an enzyme that breaks down proteins. Immunoglobulins are antibodies that have a Y-shaped structure consisting of two heavy chains and two light chains. The heavy chains are responsible for the antigen-binding region of the immunoglobulin, which is where the antibody binds to its target. Therefore, pepsin cleaves the heavy chain region of the immunoglobulin.

In electrophoresis, molecules with a higher negative charge will migrate towards the positive electrode. Albumin is the most electronegative molecule among the options given, which means it has the highest negative charge and will migrate the farthest towards the positive electrode.

IgG and IgA are the immunoglobulins that have different subtypes. IgG is the most abundant immunoglobulin in the bloodstream and is involved in long-term immunity. It can cross the placenta and provide passive immunity to the fetus. IgA is found in body secretions such as saliva, tears, and breast milk. It plays a crucial role in mucosal immunity, protecting against pathogens at the mucosal surfaces of the body. Both IgG and IgA have multiple subtypes that have different functions and provide specific immune responses.

The correct answer is that immunologic receptors on T cells recognize discontinuous (conformational) epitopes. T cells recognize epitopes presented by antigen-presenting cells (APCs) through their T cell receptors (TCRs). TCRs recognize short peptide sequences presented by major histocompatibility complex (MHC) molecules on the surface of APCs. These peptide sequences are usually linear and continuous, rather than conformational. Therefore, the statement that T cell receptors recognize discontinuous epitopes is not true.

The step "The cells are cultured in a selective medium allowing fused and non-fused cells to survive" is not correct. In hybridoma production, the selective medium is used to allow only the fused hybrid cells to survive, while the non-fused cells and myeloma cells are eliminated. This ensures that only the desired hybridoma cells, which produce the desired monoclonal antibody, are cultured and propagated.

The light chain is the correct answer because it binds to various cellular receptors and to complement. In immunoglobulins, the light chain is a smaller polypeptide chain that is part of the antibody structure. It is responsible for binding to antigens and facilitating immune responses. The heavy chain, on the other hand, is a larger polypeptide chain that is also part of the antibody structure but does not directly bind to receptors or complement. The Fab region is the antigen-binding region of the antibody, while the Fc region is responsible for other immune functions. The hinge region provides flexibility to the antibody structure.