PSL201Y1 Lecture Notes - Lecture 4: Cell Membrane, Immunoglobulin Light Chain, Polysaccharide
Document Summary
Lecture 4 specific immunity: specificity, b and t cells bind and respond to foregin or abnormal molecules (antigens). Antigens are typically complex protein or polysaccharide components of viruses, bacteria, fungi, protozoa, parasitic worms, pollen, transplanted tissue, and tumor cells. Each antigen as a unique structure and contains different recognition sites called epitopes (antigen determinants), each of which can be detected by specific lymphocytes, which then target that invader for destruction. A typically antibody is a y-shaped molecule consisting of 4 protein chains: 2 identical heavy chains, 2 identical light changes (joined by disulfide bridges. Basis of antibody antigen specificity: two heavy chains, two light chains, constant region same within a class of antibodies, variable region differs for different antigens, gives specificity to antigen-binding site, two antigen-binding sites. Figure 23. 5b: each contains variable regions (v) and constant regions (c). 2 identical v regions form 2 identical antigen-binding sites (bind to two epitopes of the same kind).
