Chapter 5

Question 1

antibodies or immunoglobulins are a family of structurally related glycoproteins produced where?

Answer 1

membrane-bound or secreted form by B

lymphocytes.

Question 2

membrane bound antibodies serve as receptors that mediate what?

Answer 2

the antigen-triggered activation of B

cells.

Question 3

Secreted antibodies function as what?

Answer 3

mediators of specific humoral immunity by engaging various effector mechanisms that serve to eliminate the bound
antigens.

Question 4

the antigen binding regions of antibody molecules are what?

Answer 4

highly variable, and any one individual has the

potential to produce more than 1011 different antibodies, each with distinct antigen specificity

Question 5

all antibodies have a common symmetric core structure of what?

Answer 5

two identical covalently linked heavy
chains and two identical light chains, each linked
to one of the heavy chains. Each chain consists of
two or more independently folded Ig domains
of about 110 amino acids containing conserved
sequences and intrachain disulfide bonds

Question 6

the N terminal domains of heavy and light chains form the what?

Answer 6

V regions of antibody molecules, which

differ among antibodies of different specificities

Question 7

The v regions of heavy and light chains each contain what?

Answer 7

three separate hypervariable regions of
about 10 amino acids that are spatially assembled
to form the antigen-combining site of the antibody
molecule

Question 8

What are the antibody classes?

Answer 8

IgM, IgD, IgG, IgE, and IgA. Both
light chains of a single Ig molecule are of the same
light chain isotype, either κ or λ, which differ in
their single C domains

Question 9

Most of the effector functions of antibodies are
mediated by the C regions of the heavy chains, but
these functions are triggered by what?

Answer 9

binding of antigens to the spatially distant combining site in the
V region.

Question 10

how are monoclonal antibodies produced?

Answer 10

from a single
clone of B cells and recognize a single antigenic
determinant

Question 11

what are antigens?

Answer 11

substances specifically bound by
antibodies or T lymphocyte antigen receptors.
Antigens that bind to antibodies represent a wide
variety of biologic molecules, including sugars,
lipids, carbohydrates, proteins, and nucleic acids

Question 12

what are macromolecular antigens?

Answer 12

contain multiple epitopes, or determinants, each of which may be recognized by an antibody

Question 13

linear epitopes of protein antigens consist of what?

Answer 13

a sequence of adjacent amino
acids, and conformational determinants are formed
by folding of a polypeptide chain

Question 14

the dissociation constant (Kd) calculated from binding

data generally represents what?

Answer 14

The affinity of the interaction between the combining site of a single antibody molecule and a
single epitope

Question 15

What are polyvalent antigens?

Answer 15

contain multiple identical epitopes to which identical antibody molecules
can bind. Antibodies can bind to two or, in the case
of IgM, up to 10 identical epitopes simultaneously,
leading to enhanced avidity of the antibody-antigen interaction

Question 16

The relative concentrations of polyvalent antigens

and antibodies may favor what?

Answer 16

the formation of immune
complexes that may deposit in tissues and cause
damage

Question 17

Antibody binding to antigen can be highly specific,

distinguishing what?

Answer 17

small differences in chemical structures, but cross-reactions may also occur in which
two or more antigens may be bound by the same
antibody

Question 18

Several changes in the structure of antibodies
made by one clone of B cells may occur in the
course of an immune response. B cells initially
produce what?

Answer 18

only membrane-bound Ig, but in activated B cells and plasma cells, synthesis is induced
of soluble Ig with the same antigen-binding specificity as the original membrane-bound Ig receptor

Question 19

Changes in the use of C region gene segments

without changes in V regions are what?

Answer 19

are the basis of

isotype switching, which leads to changes in effector function without a change in specificity

Question 20

Point
mutations in the V regions of an antibody specific
for an antigen lead to what?

Answer 20

lead to increased affinity for that

antigen (affinity maturation)