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BIOL 103 Lecture Notes Feb 4

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BIOL 103
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FEBRUARY 4, 2014 B-Cellular Immune Response  Unlike B-cells, these cells mature in the thymus, therefore are called T cells  Many of cellular components in blood originate in bone marrow (including T-lymphocytes)  NK= natural killer  T-cells have a T-receptor, which is a dimer with an A and B polypeptide chain; constant regions have a transmembrane domain  Both A and B chains have variable (different t-cell receptors) and a constant region (same, with a path to the membrane)  Variable regions of amino acid sequence differ in different clones of T-cells  Each variable region is encoded by a variable and joining gene pieces to its constant region The T-cell Receptor:  This photo can be misleading, as the receptor cannot bind to antigen unless it also binds to MHC  Shows variable region binding to antigen – however, it needs help from MHC to do this. MHC (Major Histocompatibility Complex)  MHC is on cells in our bodies, “identity tags” or genetic markers  MHC1 is found on basically all cells in body (with a nucleus; not on platelets or erythrocytes) o Binding is stabilized CD8 (on the killer T-cells it’s cytotoxic cells)  MHC2 only found on antigen presenting cells (macrophages/presentation cells), B-cells, and immune stem cells like microphages o Binding is stabilized by CD4 on t helper cells Cell-mediated Immunity  When phagocytosis takes place and digests proteins into polypeptides  Microphage/Dendritic Cell/Antigen Presentation Cell (APC) from monocytes is carried to the MHC  MHCs will grab digestive products (polypeptides) and drag to surface of macrophage  Antigen and MHC are then on the surface of the cell with digestive product  There are 1 million virgin T cells; one of them recognizes the foreign antigen, and binds to MHC on cell surface  MHC2 interaction is stabilized by CD4 protein  When this happens, virgin T-cells are induced to divide (cytokinesis by a signal transduction); then there are more T-cells which recognize the same antigen Helper T-cells (T4) functions: 1. Binds to APC (microphage) a. Binding releases chemical signal (interleukin, a peptide hormone) to simulate mitotic division of helper T, which creates a clonal population of helper Ts and memory T cells 2. Binds to B-cells, which bears an antibody and a bound antigen a. Releases interleukin which simulates B-cells to divide and produce a clonal population of B-cells FEB 6, 2014 Immunity and Cancer Cancer cells are:
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