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Download Question bank-6 –B-cell activation Q1 Explain briefly the fallowing
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Question bank-6 –B-cell activation Q1 Explain briefly the fallowing : a. Adaptive displays four characteristic attributes.. 1-Antigenic specificity: The antigenic specificity of the immune system permits it to distinguish subtle differences among antigens. Antibodies can distinguish between two protein molecules that differ in only a single amino acid. 2- Diversity: The immune system is capable of generating tremendous diversity in its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. 3- Immunologic memory: Once the immune system has recognized and responded to an antigen, it exhibits immunologic memory; that is, a second encounter with the same antigen induces a heightened state of immune reactivity. Because of this attribute, the immune system can confer life-long immunity to many infectious agents after an initial encounter. 4-Self/non self recognition: Finally, the immune system normally responds only to foreign antigens, indicating that it is capable of self/non self recognition. The ability of the immune system to distinguish self from non self and respond only to non self molecules is essential, for, as described below, the outcome of an inappropriate response to self molecules can be fatal. The antigenic specificity of the immune system permits it to distinguish subtle b b-cell diversity Generation of B cell diversity: • The number of different antibodies that can be produced by human body seems to virtually • limitless. Instead of containing a single complete gene, Ig heavy chain and light chain loci consist of families of gene segments ,each set of segments containing alternative version of parts of the immunoglobulin variable regions. b. Immunobiological function of b_cell . 1. Antigen presenting cells . 2. Producing of antibodies . Q2 Choose the correct sentences. Complete the following : 1. Adaptive immunity is not independent of innate immunity. The phagocytic cells crucial to nonspecific immune responses are intimately involved in activating the specific immune response. 2. various soluble factors produced by a specific immune response have been shown to augment the activity of these phagocytic cells. As an inflammatory response develops, for example, soluble mediators are produced that attract cells of the immune system differences among antigens. 3. Antibodies can distinguish between two protein molecules that differ in only a single amino acid. 4. An effective immune response involves two major groups of cells: T lymphocytes and antigen-presenting cells. 5. Lymphocytes are one of many types of white blood cells produced in the bone marrow by the process of hematopoiesis . 6. Lymphocytes leave the bone marrow, circulate in the blood and lymphatic systems, and reside in various lymphoid organs. 7. Because they produce and display antigen binding cell-surface receptors, lymphocytes mediate the defining immunologic attributes of specificity, lymphocytes mediate the defining immunologic attributes of specificity, diversity, memory, and self/nonself recognition. 8. B lymphocytes mature within the bone marrow; when they leave it, each expresses a unique antigen-binding receptor on its membrane This antigenbinding or B-cell receptor is a membrane-bound antibody molecule. 9. When a naive B cell (one that has not previously encountered antigen) first encounters the antigen that matches its membrane bound antibody, the binding of the antigen to the antibody causes the cell to divide rapidly; its progeny differentiate into memory B cells and effector B cells called plasma cells. 10. Plasma cells produce the antibody in a form that can be secreted and have little or no membrane-bound antibody. Although plasma cells live for only a few days, they secrete enormous amounts of antibody during this time. 11. It has been estimated that a single plasma cell can secrete more than 2000 molecules of antibody per second. 12. Secreted antibodies are the major effector molecules of humoral immunity. 13. B cells adhesion highly efficient antigen-presenting cells. 14. The primary B cell response leads to production of mainly low-affinity IgM antibodies. 15. some responding B cells undergo heavy chain class switching and V region somatic mutation to produce higher-affinity IgG, IgA or IgE anti-bodies. Memory B cells are selected from this latter population. 16. This interaction induces activation of the B-cells re-encounter their specific antigen ,they rapidly produce high-affinity IgG, IgA or IgE . This requires fewer T helper cells and lower levels of lymphokines than the primary response. Q3 Explain in diagram the following a. Activation of B-cell. 2Diversity: The immune system is capable of generating tremendous diversity in its b B B B b- Isotype switching of immunoglobulin class recognition molecules, allowing it to recognize billions of unique structures on c- Primary and secondary immune response 2- Di The immune system is capable of generating tremendous diversity in its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. The antigenic specificity of the immune system permits it to distinguish subtle differences among antigens. Antibodies can distinguish between two protein molecules that differ in only a single amino acid. 2- Diversity: The immune system is capable of generating tremendous diversity in its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. nic specificity of the immune system permits it to distinguish subtle differences among antigens. Antibodies can distinguish between two protein molecules that differ in only a .single amino acid :Diversity -2 The immune system is capable of generating tremendous diversity in its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. The antigenic specificity of the immune system permits it to distinguish subtle differences among antigens. Antibodies can distinguish between two protein molecules that differ in only a single amino acid. 2- Diversity: The immune system is capable of generating tremendous diversity in its recognition molecules, allowing it to recognize billions of unique structures on foreign antigens. our characteristic attributes