Practice question

Antibody molecule comprises Fab and Fc segments after papain cleavage. Fab includes entire light chain paired with variable and first constant domain of heavy chain. Hypervariable complementarity determining regions within variable domains fold to create paratope complementary to epitope shape, charge and hydrophobicity. This interaction determines specificity, affinity and neutralization capacity. Fc region mediates effector functions like complement fixation and Fc receptor engagement, not antigen recognition. All immunoglobulin isotypes and monoclonal preparations possess Fab, and it lacks intrinsic enzymatic activity, functioning solely as antigen-binding unit guiding humoral immunity and diagnostic immunoassays.