Exam 2 Chp. 5 Antibody Structure & Function

structure and functions of immunoglobulins, their classes, and their role in the immune response.

What are the major components of a typical immunoglobulin's structure?

It is composed of 4 chains: 2 identical heavy chains and 2 identical light chains.

What determines the class and function of an antibody?

The constant region of the immunoglobulin.

What is the function of the Fab fragment of an antibody?

Fab fragments are the arms that bind to antigens.

What is the role of the Fc fragment in an antibody?

The Fc fragment recruits immune cells to destroy the antigen.

What is the electrophoretic fraction containing the majority of immunoglobulins?

Most immunoglobulins are located in the gamma (γ) region of the electrophoretic profile.

How do isotypes differ in immunoglobulins?

Isotypes differ in antibody constant regions, unique to each Ig class but the same in individuals of the same species.

What is the primary function of IgA?

IgA prevents pathogen adherence in mucosal secretions.

In what form is IgM typically found?

IgM is usually secreted as a pentamer.

How does the structure of IgM differ from that of IgG?

IgM has a pentameric structure providing 10 antigen-binding sites, while IgG is a monomer.

What is the significance of the clonal selection hypothesis in antibody formation?

It states that B cells are preprogrammed for specific antibody synthesis.

What is a major function of IgE?

IgE is critical in allergic reactions and defense against parasites.

What region of the immunoglobulin is responsible for binding to Fc receptors on immune cells?

The constant region of the heavy chains.

What are the variations called that occur in the variable region of antibodies?

Idiotypes.

Which immunoglobulin is best at opsonization?

IgG.

What is the function of the secretory component of IgA?

It protects IgA from enzymatic degradation in secretions.

Which immunoglobulin class is primarily involved in the initial response to an antigen?

IgM.

What characterizes the primary antibody response?

It has a lag phase and low-affinity IgM production initially.

What are the major laboratory uses for monoclonal antibodies?

Monoclonal antibodies are used in diagnostic assays, blood typing, and monitoring of immune responses.

What happens during proteolytic cleavage of an IgG molecule?

It results in two Fab fragments and one Fc fragment.

What is the main function of IgD?

IgD primarily acts as a receptor on immature B cells.