Capsulated yeast among the following -
Ans. is 'c' i.e., Cryptococcus * Antibody specificity is due to variability of the aminoacid sequences at the variable unit (at aminoterminal) of both H and L chains (not only H or L chains).Antibody (Immunoglobulin)* Immunoglobulins are molecles that are produced by plasma cells in response to an immunogen.* Immunoglobulins are glycoproteins* Each immunoglobulin is composed of two light chains (L) and two heavy chains H.* The L chain has a molecular weight of 25000, and the H. chain of 50000.* The L chain is attached to H. chain by disulphide bond.* The two H chains are joined together by disulphide bonds.* Immunoglobulin isotype (ie. G, M, A, D, E) is determined by the type of Ig heavy chain present.* Hinge point is the point at which heavy and light chains join. This point can be digested by papain digestion, to produce one Fc fragment and two Fab fragments:Immunoglobulin classH. chainIgGg (gamma)IgAa (alpha)IgMm (mu)IgDd (delta)IgEe (epsilon)* The isotype variation or class of antibody is due to variation in the amino acid sequence in the constant region of the heavy chain. Because there are five potential variation in the aminoacid sequence in the constant region there are five classes of antibody i.e. IgG, IgM, IgA, IgD, IgE.* These H chain differences are called isotypes and are designated by the greek letters gamma (g), alpha (a) mu (m), epsilon (e) and delta (d) respectively.* The L chains are similar in all classes of immunoglobulins either kappa or lambda (kappa being more common).* Antigen combining site is at amino-terminus and is composed by both L and H chains.* Both H and L chains consist of two units; constant and variable :H chain - One variable (VH) and three or four constant units (CH)L chain - One variable (VL ) and one constant (C2) unit.* The variable region is further subdivided into hypervariable region and frame work region.* Hypervariable regions at aminoterminal are involved in formation of antigen binding sites.* L chain has three hypervariable regions and H chain has four. Hypervariable regions are also called as 'Hot spots'.* Sites on the hypervariable regions which make actual contact with the epitopes are called complementarity determining regions (CDRs).CDR, i.e. antigen binding site is also called idiotype.* The infinite range of the antibody specificity of immunoglobulins depends on the variability of the aminoacid sequences at the variable units of H and L chains.* Fc fragment is composed of the carboxyterminal. It determines the biological activity such as complement fixation, placental transfer, skin fixation and catabolic rate.* CH 2 of Ig G and CH4 of IgM bind to C1q portion of C1.
Histoplasma
Candida
Cryptococcus
Sporothrix
Mycology