ch 15 micro quiz

B cell receptors differ from T cell receptors in that

B cell receptors are comprised of four polypeptides, whereas T cell receptors have only two polypeptides in their quaternary structure B cell receptors have two antigen binding sites, whereas T cell receptors have only one antigen binding site. B cell receptors are immunoglobulin in nature, whereas T cell receptors are not immunoglobulin molecules. B cell receptor immunoglobulins can be secreted as antibodies, whereas T cell receptors are never secreted. - All of the choices represent differences between B cell and T cell receptors.

The array of potential antibodies to the variety of possible antigens is amazing. Which statement explains this development?

Recombination of genes coding for the variable regions of immunoglobulins occurs during the developmental stage of lymphocyte production.

Helper T cells

activate B cells and other T cells

A foreign molecule that causes a specific immune response is a(n) ______

antigen

Superantigens are

bacterial toxins that activate T cells at a 100 times greater rate than other antigens

What process generates many B cells and T cells that are activated against specific antigens?

clonal expansion

Which of the following do not serve as antigen presenting cells?

dendritic cells macrophages B lymphocytes - basophils

Antigen presenting cells

include dendritic cells include macrophages engulf and modify antigen to become more immunogenic hold and present processed antigen on their cell membrane surface - all of the choices are correct

Which of the following is not true of the antigen-independent period of lymphocyte development?

mature lymphocytes populate lymphatic organs and encounter antigens

Which process involves antibodies coating microorganisms in order to facilitate phagocytosis?

opsonization

The ability of TC cells to initiate apoptosis in virally-infected cells and cancer cells is dependent on their ability to produce __________ and __________; proteins that punch holes in the target cell membrane

perforin, granzyme

The antibody-secreting progeny cells of a B-cell clone are called

plasma cells

Class II MHC genes code for

receptors located primarily on macrophages and B cells

Class I MHC genes code for

self receptors recognized by T lymphocytes

The third line of defense against foreign invaders can be described as having _______ and ________

specificity, memory