Final answer:
Agglutination involves the clumping together of pathogens by antibodies that can bind to multiple antigens, facilitated by IgG and IgM. Opsonization, however, marks pathogens for easier phagocytosis by phagocytic cells through antibody coating.
Step-by-step explanation:
Agglutination is the process that is dependent on antibodies being capable of binding more than one antigen. Immunoglobulin G (IgG), with its two antigen-binding sites, or Fab sites, can connect multiple pathogen cells, resulting in the clumping together of these cells into large aggregates. This aggregation facilitates the easier filtration of pathogens from the blood by the spleen and kidneys and aids in the phagocytosis by phagocytes. Immunoglobulin M (IgM), due to its pentameric structure, provides even more antigen-binding sites—ten per molecule—making it exceptionally efficient at agglutination. In comparison, opsonization refers to the marking of pathogens for destruction by phagocytic cells, such as macrophages or neutrophils, with antibodies. It involves the coating of pathogens with molecules to enhance phagocyte binding and facilitate phagocytosis, rather than direct agglutination of pathogens.