Chapter 4 Flashcards by Julie Hernandez

Which of the following statements regarding immunoglobulin light chains is correct?

a. Kappa light chain associates with only particular heavy-chain isotypes.
b. There is no functional difference between kappa and lambda.
c. A given antibody may contain just kappa, or just lambda, or both.
d. Most antibodies in humans contain kappa light chains.
e. Light chains possess only framework regions, not hypervariable regions

There is no functional difference between kappa and lambda.

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An epitope is the specific part of the antigen that is recognized by an antibody and binds to the complementarity-determining regions in the antibody variable domains. Epitopes are sometimes referred to as antigenic determinants. Epitopes can be part of a protein or can be carbohydrate or lipid structures present in the glycoproteins, polysaccharides, glycolipids, and proteoglycans of pathogens.

True

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Indicate which of the following statements is false

a. Light chains contain V and J segments, whereas heavy chains contain V, D, and J segments.
b. The Vk gene segments are duplicated in about 50% of the human population.
c. All immunoglobulin loci include a leader sequence.
d. On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence.
e. Immunoglobulin heavy-chain loci undergo two rounds of somatic recombination, whereas light-chain loci undergo only one.

On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence.

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The five isotypes of immunoglobulin differ from each other in their _____.

a. light-chain constant regions
b. heavy-chain constant regions
c. light-chain variable regions
d. heavy-chain variable regions
e. heavy-chain variable and constant regions

heavy-chain constant regions

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Gene rearrangement by somatic recombination involves recombination signal sequences (RSSs) that flank V, D, and J segments and are recognized by the enzymes involved in cutting and rejoining the gene segments. An RSS is composed of a conserved nonamer sequence and heptamer sequence separated by a spacer region. There are two types of RSS, one with a spacer of 12 bp and one with a spacer of 23 bp. To ensure that segments are brought together in the right order, an RSS with a 12-bp spacer is always brought together with one with a 23-bp spacer. This is called the 12/23 rule. This ensures that in the heavy-chain locus, V rearranges to DJ and not directly to J or another V, and in the light-chain locus, V rearranges to J and not to another V.

True

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With the exception of B cells, all other cells of the body have the immunoglobulin genes in the ______________.

a. germline configuration
b. monoclonal form
c. recombined configuration
d. expressed configuration
e. chimeric form

germline configuration

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An individual with a genetic defect that results in a lack of somatic recombination between V, D, and J segments would be unable to rearrange either immunoglobulin or T-cell receptor genes somatically. There would be a severe combined immunodeficiency (SCID) owing to the absence of mature B cells and T cells.

True

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In what way does the kappa light chain differ from the lambda light chain?

a. Kappa performs a different function from lambda when bound to the immunoglobulin heavy chain.
b. Kappa, but not lambda, is encoded on the same chromosome as the heavy-chain locus.
c. Kappa contains a VJ region, whereas lambda contains a VDJ region.
d. The kappa locus encodes a single C segment, whereas the lambda locus has more than one.
e. Kappa contains a transmembrane domain but lambda does not.

The kappa locus encodes a single C segment, whereas the lambda locus has more than one.

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Linear epitopes are epitopes in proteins that comprise a contiguous amino acid sequence. They are also called continuous epitopes. In contrast, a conformational epitope is formed by amino acids that are brought together as a result of protein folding and are not adjacent in the protein sequence. Conformational epitopes are also known as discontinuous epitopes.

True

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All of the following are utilized in the binding of antibodies to antigens, except ___________.

a. interchain disulfide bonds
b. hydrogen bonding
c. hydrophobic interactions
d. electrostatic forces (salt bridges)
e. van der Waals interactions

interchain disulfide bonds

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Which of the following is not a component of V(D)J recombinase?

a. Artemis
b. Terminal deoxynucleotidyl transferase
c. RAG-1/RAG-2
d. DNA ligase IV
e. DNA-dependent protein kinase and the associated Ku protein

Terminal deoxynucleotidyl transferase

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The name given to a fully activated and differentiated B cell that secretes antibody is __________________.

a. T cell
b. antigen-presenting cell
c. hematopoietic cell
d. secretory cell
e. plasma cell

plasma cell

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All of the following comprise heavy-chain isotypes of immunoglobulin except _______.

a. alpha
b. beta
c. gamma
d. delta
e. epsilon

beta

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The _______ contribute to antigen specificity of immunoglobulins, and _______ make up the more conservative flanking regions.

a. hypervariable loops; framework regions
b. constant domains; variable domains
c. heavy chains; light chains
d. variable gene segments; joining gene segments
e. antigenic determinants; complementarity determining regions

hypervariable loops; framework regions

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Which of the following corresponds to the antigen-binding site of immunoglobulins?

a. VH:CH
b. VH:VL
c. VL:CL
d. CH:CL
e. VH:CL

VH:VL

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Which of the following does not describe B-cell receptors?

a. B-cell receptors are membrane-bound and secreted.
b. B-cell receptors consist of a variable region and a constant region.
c. B-cell receptors lack specificity and can bind to a number of different antigens.
d. B-cell receptors possess specificity and can therefore bind only to unique epitopes.
e. B cell receptors undergo affinity maturation as a consequence of somatic hypermutation.

B-cell receptors lack specificity and can bind to a number of different antigens.

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Which immunoglobulin is transported most efficiently across mucosal epithelium?

a. IgA
b. IgD
c. IgE
d. IgG
e. IgM

IgA

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Which of the following determines the isotype of an immunoglobulin?

a. the composition of the hypervariable regions
b. whether the immunoglobulin is membrane-bound or secreted
c. its light chain
d. its heavy chain
e. the composition of the cytoplasmic tails of Ig? and Ig?

its heavy chain

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a. in CDR3; throughout the V region
b. in CDR3; in CDR1 and CDR2 of VH and VL domains
c. in CDR1 and CDR2; in CDR3
d. in CDR1 and CDR2; throughout the V region
e. in all three CDRs; in C regions

in CDR3; throughout the V region

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A newborn derives passive immunity from its mother as a result of placental transfer of _____ during pregnancy.

a. IgA
b. IgD
c. IgE
d. IgG
e. IgM

IgG

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The mutational mechanism that results in the production of antibodies that bind antigen with higher affinity is called _____.

a. somatic recombination
b. isotype switching
c. somatic hypermutation
d. clonal selection
e. antigen processing

somatic hypermutation

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Igalpha and Igbeta proteins are highly variable, because they interact directly with antigen. Igalpha and Igbeta perform specific signaling functions, which require particular amino acid sequences and also have evolved a sequence and structure that enable them to interact with all the different immunoglobulin isotypes. Extensive variation in Igalpha and/or Igbeta could therefore compromise their interaction with immunoglobulins and their signal transduction capabilities.

False

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Igalpha and Igbeta are essential for escorting immunoglobulins from the endoplasmic reticulum membrane to the cell membrane, where they remain associated with the immunoglobulin to form the functional B-cell antigen receptor. The long cytoplasmic tails of Igalpha and Igbeta contain amino acid motifs that interact with intracellular signaling proteins after the receptor has been activated by the binding of antigen to the immunoglobulin.

True

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The process of _____ results in the amplification of particular B cells with specificity for antigen.

a. germline recombination
b. somatic recombination
c. clonal selection
d. antigen processing
e. antigen presentation

clonal selection

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As an adaptive immune response progresses, the production of variant antibodies that compete more effectively for antigen occurs, and B cells producing these antibodies are preferentially selected on the basis of their improved binding to antigen. This phenomenon is referred to as \_\_\_\_\_\_\_. a. isotype switching b. neutralization c. allelic exclusion d. affinity maturation e. somatic rearrangement

affinity maturation

Which of the following statements about the production and use of monoclonal antibodies is incorrect? a. Production of monoclonal antibodies requires a purified form of antigen. b. A monoclonal antibody has specificity for only one epitope of an antigen. c. B cells are fused with a tumor cell called a myeloma, to immortalize the resulting hybridoma. d. Monoclonal antibodies made in mice have limited therapeutic potential. e. Humanized monoclonal antibodies reduce complications associated with using mouse monoclonal antibodies.

Production of monoclonal antibodies requires a purified form of antigen.

The process used to produce either surface or secreted forms of the immunoglobulin heavy chain is called \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. a. alternative RNA processing b. isotype switching c. somatic recombination d. somatic hypermutation e. opsonization

alternative RNA processing

Naive B cells are recognized by their expression of \_\_\_\_\_\_\_\_\_\_\_\_\_\_. a. no immunoglobulins on the cell surface because somatic recombination has not yet commenced b. both membrane-bound and secreted forms of immunoglobulin c. both IgM and IgD on the cell surface d. V(D)J recombinase e. uracil-DNA-glycosylase (UNG)

both IgM and IgD on the cell surface

Which of the following can be found in serum in a monovalent form? a. IgG4 b. IgD c. IgA1 d. antibodies made up of four C domains e. IgG3

IgG4

A circulating B cell that has never before encountered antigen expresses _____ on the cell surface. a. IgM and IgD b. IgM c. IgD d. IgM and IgG e. IgG

IgM and IgD

The rejoining and repair of DNA during the recombination process leads to additional variation in sequence at the junctions between the rearranged gene segments. This is called junctional diversity and contributes considerably to the final diversity of T cell receptor specificities. Two sources of junctional diversity are introduced: P (palindromic) and N (nontemplated) nucleotides. P nucleotides are generated through endonuclease activity and repair around a hairpin loop at the ends of the gene segments to be joined. N nucleotides are nucleotides added at random at the junctions by terminal deoxynucleotidyl transferase (TdT) activity.

True

On the beta-chain gene locus, recombination signal sequences flank _______ of the V segment, _______ of the D segment, and _______ of the J segment. a. the 5' side; both sides; the 3' side b. the 5' side; the 5' side; the 5' side c. the 3' side; both sides'; the 3' side d. both sides; both sides; both sides e. the 3' side; both sides; the 5' side

the 3' side; both sides; the 5' side

IgG possesses _______ binding sites for antigen, and the T-cell receptor possesses _______ binding sites for antigen. a. 1; 1 b. 2; 1 c. 1; 2 d. 2; 2 e. 2; 4

2; 1

The antigen-recognition site of T-cell receptors is formed by the association of which of the following domains? a. Valpha and Calpha b. Vbeta and Cbeta c. Calpha and Cbeta d. Valpha and Cbeta e. Valpha and Vbeta

Valpha and Vbeta

In reference to the interaction between T-cell receptors and their corresponding ligands, which of the following statements is correct? a. The organization of the T-cell receptor antigen-binding site is distinct from the antigen-binding site of immunoglobulins. b. The orientation between T-cell receptors and MHC class I molecules is different from that of MHC class II molecules. c. The CDR3 loops of the T-cell receptor alpha and beta chains form the periphery of the binding site making contact with the alpha helices of the MHC molecule. d. The most variable part of the T-cell receptor is composed of the CDR3 loops of both the alpha and beta chains. e. The most constant part of the T-cell receptor is composed of the CDR3 loops of both the alpha and beta chains.

The most variable part of the T-cell receptor is composed of the CDR3 loops of both the alpha and beta chains.

The CDR3 loops of the T-cell receptor contact the \_\_\_\_\_\_\_. a. side chains of amino acids in the middle of the peptide b. co-receptors CD4 or CD8 c. membrane-proximal domains of the MHC molecule d. constant regions of antibody molecules e. alpha helices of the MHC molecule

side chains of amino acids in the middle of the peptide

Which of the following statements regarding T-cell receptor recognition of antigen is correct? a. alpha:beta T-cell receptors recognize antigen only as a peptide bound to an MHC molecule. b. alpha:beta T-cell receptors recognize antigens in their native form. c. alpha:beta T-cell receptors, like B-cell immunoglobulins, can recognize carbohydrate, lipid, and protein antigens. d. Antigen processing occurs in extracellular spaces. e. Like alpha:beta T cells, gamma:delta T cells are also restricted to the recognition of antigens presented by MHC molecules.

alpha:beta T-cell receptors recognize antigen only as a peptide bound to an MHC molecule.

How many complementarity-determining regions contribute to the antigen-binding site in an intact T-cell receptor? a. 2 b. 3 c. 4 d. 6 e. 12

Which of the following statements regarding Omenn syndrome is incorrect? a. A bright red, scaly rash is due to a chronic inflammatory condition. b. Affected individuals are susceptible to infections with opportunistic pathogens. c. It is invariably fatal unless the immune system is rendered competent through a bone marrow transplant. d. It is the consequence of complete loss of RAG function. e. There is a deficiency of functional B and T cells.

It is the consequence of complete loss of RAG function.

All of the following statements regarding gamma:delta T cells are correct except \_\_\_\_\_\_\_\_\_\_\_. a. they are more abundant in tissue than in the circulation b. the delta chain is the counterpart to the beta chain in alpha:beta T-cell receptors because it contains V, D, and J segments in the variable region c. they share some properties with NK cells d. activation is not always dependent on recognition of a peptide:MHC molecule complex e. expression on the cell surface is not dependent on the CD3 complex

expression on the cell surface is not dependent on the CD3 complex

Junctional diversity during gene rearrangement results from the addition of \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. a. switch region nucleotides b. P and N nucleotides c. V, D, and J nucleotides d. recombination signal sequences e. mutations in complementarity-determining regions

P and N nucleotides

If viewing the three-dimensional structure of a T-cell receptor from the side, with the T-cell membrane at the bottom and the receptor pointing upwards, which of the following is inconsistent with experimental data? a. The highly variable CDR loops are located across the top surface. b. The membrane-proximal domains consist of Calpha and Cbeta. c. The portion that makes physical contact with the ligand comprises Vbeta and Cbeta, the domains farthest from the T-cell membrane. d. The transmembrane regions span the plasma membrane of the T cell. e. The cytoplasmic tails of the T-cell receptor alpha and beta chains are very short

The portion that makes physical contact with the ligand comprises Vbeta and Cbeta, the domains farthest from the T-cell membrane.

During T-cell receptor \_\_\_\_\_-gene rearrangement, two D segments may be used in the final rearranged gene sequence, thereby increasing overall variability of this chain. a. alpha b. beta c. gamma d. delta e. epsilon

delta

T cells recognize antigen when the antigen \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_. a. forms a complex with membrane-bound MHC molecules on another host-derived cell b. is internalized by T cells via phagocytosis and subsequently binds to T-cell receptors in the endoplasmic reticulum c. is presented on the surface of a B cell on membrane-bound immunoglobulins d. forms a complex with membrane-bound MHC molecules on the T cell e. bears epitopes derived from proteins, carbohydrates, and lipids

forms a complex with membrane-bound MHC molecules on another host-derived cell

The five classes (isotypes) of immunoglobulins comprise a. IgA, IgD, IgE, IgG, IgM b. IgA, IgC, IgD, IgE, IgG c. IgA, IgD, IgE, IgH, IgM d. IgA, IgD, IgE, IgG, IgK e. IgA, IgD, IgE, IgG, IgS

IgA, IgD, IgE, IgG, IgM

The name given to a fully activated and differentiated B cell that secretes antibody is a. T cell b. antigen-presenting cell c. hematopoietic cell d. secretory cell e. plasma cell

plasma cell

All of the following comprise heavy-chain isotypes of immunoglobulin except a. α b. β c. γ d. δ e. ε

Which of the following statements regarding immunoglobulin light chains is correct? a. κ associates with only particular heavy-chain isotypes. b. There is no functional difference between κ and λ. c. A given antibody may contain just κ, or just λ, or both. d. Most antibodies in humans contain λ light chains. e. Light chains possess only framework regions, not hypervariable regions.

There is no functional difference between κ and λ.

\_\_\_\_\_, \_\_\_\_\_, and _____ are the three most abundant antibodies in blood: a. IgA, IgD, and IgE b. IgA, IgE, and IgG c. IgA, IgG, and IgM d. IgE, IgG, and IgM e. IgD, IgE, and IgM

IgA, IgG, and IgM

The five isotypes of immunoglobulin differ from each other in their \_\_\_\_\_: a. light-chain constant regions b. heavy-chain constant regions c. light-chain variable regions d. heavy-chain variable regions e. heavy-chain variable and constant regions

heavy-chain constant regions

Which one of the following features renders all IgG antibodies less susceptible to proteolysis than the other antibody classes? a. length of the hinge region b. ability to exchange chains with other IgG antibodies c. presence of additional disulfide bonds d. capacity to activate complement e. degree of accessibility for binding to C1

presence of additional disulfide bonds

Which of the following is mismatched? a. 100–110-amino-acid motif: immunoglobulin domain b. discontinuous epitope: amino acids that are separated in the protein chain but come together in the folded protein c. heavy-chain classes: IgG, IgA, IgM, IgE, IgD d. multivalent antigen: antigen that carries several epitopes of the same or different specificity e. four C domains: IgM and IgD

four C domains: IgM and IgD

The _______ contribute to antigen specificity of immunoglobulins, and _______ make up the more conservative flanking regions. a. hypervariable loops; framework regions b. constant domains; variable domains c. heavy chains; light chains d. variable gene segments; joining gene segments e. antigenic determinants; complementarity determining regions

hypervariable loops; framework regions

The immunoglobulin heavy-chain gene consists of _______ segments, whereas the immunoglobulin light-chain gene consists of _______ segments. a. κ; λ b. VDJ; VJ c. VJ; VDJ d. P; N e. RAG-1; RAG-2

VDJ; VJ

On the heavy-chain immunoglobulin gene locus, recombination signal sequences flank _______ of the V segment, _______ of the D segment, and _______ of the J segment. a. the 5′ side; both sides; the 3′ side b. the 5′ side; the 5′ side, the 5′ side c. the 3′ side; both sides; the 3′ side d. both sides; both sides; both sides e. the 3′ side; both sides; the 5′ side

the 3′ side; both sides; the 5′ side

Which of the following describes two recombination signal sequences required for a permitted somatic recombination event? a. VH 7-12-9::9-23-7 JH b. Vλ7-23-9::9-23-7 Jλ c. DH 7-12-9::9-23-7 JH d. Vκ7-12-9::7-23-9 Jκ e. VH 9-23-7::7-12-9 DH

DH 7-12-9::9-23-7 JH

The enzyme responsible for recombining V, D, and J segments during somatic recombination is called a. V(D)J recombinase b. terminal deoxynucleotidyl transferase c. exonuclease d. DNA polymerase e. DNA ligase

V(D)J recombinase

Which of the following is not a component of V(D)J recombinase? a. Artemis b. Terminal deoxynucleotidyl transferase c. RAG-1/RAG-2 d. DNA ligase IV e. DNA-dependent protein kinase and the associated Ku protein

Terminal deoxynucleotidyl transferase

Which of the following corresponds to the antigen-binding site of immunoglobulins? a. VH:CH b. VH:VL c. VL:CL d. CH:CL e. VH:CL

VH:VL

Another term commonly used to describe hypervariable loops is a. multivalency b. framework regions c. hinge region d. complementarity-determining regions e. signal joint

complementarity-determining regions

Which of the following is not a term used to describe the molecules or components of molecules to which antibodies bind? (Select all that apply.) a. CDR loops b. antigen c. hypervariable region d. antigenic determinant e. conformational epitope

a. CDR loops c. hypervariable region

All of the following are utilized in the binding of antibodies to antigens except a. interchain disulfide bonds b. hydrogen bonding c. hydrophobic interactions d. electrostatic forces (salt bridges) e. van der Waals interactions

interchain disulfide bonds

A _____ antibody is one that facilitates a chemical reaction involving the antigen to which it binds and interacts. a. conformational b. multivalent c. catalytic d. hypervariable e. monoclonal

catalytic

Production by the patient of antibodies against therapeutic mouse monoclonal antibodies is the major limitation for their use in humans. These human anti-antibodies are directed against the _____ of the mouse antibody. a. V regions b. D regions c. C regions d. J regions e. MC regions

C regions

Identify the incorrect statement regarding flow cytometry. a. Samples must be incubated with fluorescent molecules (such as fluorescent antibodies) before analysis. b. It is possible to label samples with two fluorescent tags and determine whether cells are negative or positive for either one tag or the other, or both. c. A one-dimensional histogram measures the amount of fluorescence versus cell number. d. Samples must consist of a single cell type and not be composed of multiple cell types. e. A laser is used to detect labeled cells. f. A stream of cells in single file is generated by a nozzle.

Samples must consist of a single cell type and not be composed of multiple cell types.

With the exception of B cells, all other cells of the body have the immunoglobulin genes in the a. germline configuration b. monoclonal form c. recombined configuration d. expressed configuration e. chimeric form

germline configuration

Indicate which of the following statements is false. (Select all that apply.) a. Immunoglobulin heavy- and light-chain loci are encoded on the same chromosome. b. Light chains contain V and J segments, whereas heavy chains contain V, D, and J segments. c. The Vκ gene segments are duplicated in about 50% of the human population. d. All immunoglobulin loci include a leader sequence. e. On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence. f. Immunoglobulin heavy-chain loci undergo two rounds of somatic recombination, whereas light-chain loci undergo only one

a. Immunoglobulin heavy- and light-chain loci are encoded on the same chromosome. e. On the heavy-chain locus, V rearranges to D first, and then J joins the combined VD sequence.

Which of the following statements is correct concerning membrane-coding (MC) exons of immunoglobulin genes? a. MC exons are located upstream (5′) of the constant-domain exons. b. MC exons code for amino acids that anchor and stabilize the light chain to the membrane of B cells. c. MC exons specify transmembrane hydrophobic amino acids that associate with the B-cell membrane. d. MC exons are removed from primary RNA transcripts as a consequence of alternative mRNA splicing when secreted antibodies are produced by plasma cells. e. Somatic hypermutation causes alteration in the coding sequence of MC exons.

MC exons specify transmembrane hydrophobic amino acids that associate with the B-cell membrane.

In what way does the κ light chain differ from the λ light chain? a. κ performs a different function from λ when bound to the immunoglobulin heavy chain. b. κ, but not λ, is encoded on the same chromosome as the heavy-chain locus. c. κ contains a VJ region, whereas λ contains a VDJ region. d. The κ locus encodes a single C segment, whereas the λ locus has more than one. e. κ contains a transmembrane domain but lambda does not.

The κ locus encodes a single C segment, whereas the λ locus has more than one.

In contrast with leader peptides and the C regions, the V regions in immunoglobulin heavy-chain genes a. encode hydrophobic amino acids that anchor the immunoglobulin chains to B-cell membranes b. comprise the smallest number of gene segments in the human immunoglobulin loci c. are composed of V, D, and J gene segments that must undergo gene rearrangement to generate a transcribable exon d. do not undergo somatic hypermutation e. are not subject to allelic exclusion

are composed of V, D, and J gene segments that must undergo gene rearrangement to generate a transcribable exon

Which of the following is matched incorrectly? a. κ light-chain locus: chromosome 2 b. coding joint: nonhomologous end-joining of V and J gene segments c. λ light-chain locus: four or five C gene segments d. affinity maturation: addition of P and N nucleotides e. recombination signal sequence: heptamer–spacer–nonamer

affinity maturation: addition of P and N nucleotides

The enzyme responsible for adding N nucleotides is a. V(D)J recombinase b. terminal deoxynucleotidyl transferase c. uracil-DNA-glycosylase (UNG) d. DNA ligase e. activation-induced cytidine deaminase (AID)

terminal deoxynucleotidyl transferase

Which of the following enzymes facilitates the process of affinity maturation? a. DNA ligase b. V(D)J recombinase c. terminal deoxynucleotidyl transferase d. activation-induced cytidine deaminase (AID) e. exonuclease

activation-induced cytidine deaminase (AID)

The process of gene rearrangement in immunoglobulin and T-cell receptor genes is called a. somatic hypermutation b. isotype switching c. somatic recombination d. apoptosis e. clonal selection

somatic recombination

Junctional diversity during gene rearrangement results from the addition of a. switch region nucleotides b. P and N nucleotides c. V, D, and J nucleotides d. recombination signal sequences e. mutations in complementarity-determining regions

P and N nucleotides

A circulating B cell that has never before encountered antigen expresses _____ on the cell surface: a. IgM and IgD b. IgM c. IgD d. IgM and IgG e. IgG f. IgE

IgM and IgD

All of the following processes occur in mature B cells after antigen encounter except a. alternative splicing b. affinity maturation c. proliferation d. somatic recombination e. isotype switching

somatic recombination

Identify the correct order of gene segments in a rearranged heavy-chain gene in a naive B cell. a. L–VDJ–Cμ–Cδ b. VDJ–Cμ–Cδ–L c. L–VDJ–Cδ–Cμ d. VDJ–L–Cμ–Cα1 e. L–VDJ–Cμ–Cα1

L–VDJ–Cμ–Cδ

Which of the following does not describe B-cell receptors? a. B-cell receptors are membrane-bound and secreted. b. B-cell receptors consist of a variable region and a constant region. c. B-cell receptors lack specificity and can bind to a number of different antigens. d. B-cell receptors possess specificity and can therefore bind only to unique epitopes. e. B cell receptors undergo affinity maturation as a consequence of somatic hypermutation.

B-cell receptors lack specificity and can bind to a number of different antigens.

Which of the following determines the isotype of an immunoglobulin? a. the composition of the hypervariable regions b. whether the immunoglobulin is membrane-bound or secreted c. its light chain d. its heavy chain e. the composition of the cytoplasmic tails of Igα and Igβ

its heavy chain

Naive B cells are recognized by their expression of a. no immunoglobulins on the cell surface because somatic recombination has not yet commenced b. both membrane-bound and secreted forms of immunoglobulin c. both IgM and IgD on the cell surface d. V(D)J recombinase e. uracil-DNA-glycosylase (UNG)

both IgM and IgD on the cell surface

Which of the following statements regarding Igα and Igβ proteins are correct? (Select all that apply.) a. They associate with all isotypes of antibodies on the cell membrane. b. They are not required to form the fully functional B-cell receptor. c. They facilitate signal transduction through their long cytoplasmic tails. d. They are linked to one another by disulfide linkages. e. They are made by somatic rearrangement.

a. They associate with all isotypes of antibodies on the cell membrane. c. They facilitate signal transduction through their long cytoplasmic tails. d. They are linked to one another by disulfide linkages.

The highest degree of diversity resulting from somatic recombination is concentrated ____________ of the VH and VL domains, whereas the point mutations caused by somatic hypermutation are found \_\_\_\_\_\_\_\_\_\_\_\_. a. in CDR3; throughout the V region b. in CDR3; in CDR1 and CDR2 of VH and VL domains c. in CDR1 and CDR2; in CDR3 d. in CDR1 and CDR2; throughout the V region e. in all three CDRs; in C regions

in CDR3; throughout the V region

affinity maturation

All of the following are required for isotype switching except a. switch-region recombination b. J chain c. activation-induced cytidine deaminase (AID) d. B-cell proliferation e. uracil-DNA glycosylase (UNG)

J chain

Which of the following does not activate complement? (Select all that apply.) a. IgG1 b. IgG2 c. IgG3 d. IgG4 e. IgA f. IgE g. IgM h. IgD

d. IgG4 f. IgE h. IgD

Which of the following can be found in serum in a monovalent form? a. IgG4 b. IgD c. IgA1 d. antibodies made up of four C domains e. IgG3

IgG4

Neutralizing antibodies a. interfere with antigen degradation b. facilitate uptake of antigen through Fc regions c. stimulate complement activation d. inhibit interaction of antigen with human cell surfaces e. sensitize mast cells and basophils

inhibit interaction of antigen with human cell surfaces

Which of the following statements regarding immunoglobulins is correct? a. Immunoglobulins make up five classes (or isotypes) called IgA, IgD, IgE, IgG, and IgM. b. Regardless of their isotype, immunoglobulins all have the same effector function. c. Antibodies consist of four identical heavy chains and four identical light chains. d. Peptide bonds hold the heavy and light chains together. e. The constant regions make up the antigen-binding site.

Immunoglobulins make up five classes (or isotypes) called IgA, IgD, IgE, IgG, and IgM.

Which of the following is mismatched? a. surface immunoglobulin: B-cell antigen receptor b. affinity maturation: isotype switching c. constant region of antibodies: binding to complement proteins d. activation-induced cytidine deaminase: somatic hypermutation e. switch sequences: class switching

affinity maturation: isotype switching

Production of monoclonal antibodies requires a purified form of antigen.

The mutational mechanism that results in the production of antibodies that bind antigen with higher affinity is called \_\_\_\_\_: a. somatic recombination b. isotype switching c. somatic hypermutation d. clonal selection e. antigen processing

somatic hypermutation

The process of _____ results in change in the constant region of the heavy-chain of antibodies, causing a change in the effector function and transport properties of antibodies: a. complement fixation b. neutralization c. isotype switching d. somatic hypermutation e. somatic recombination

isotype switching

The process used to produce either surface or secreted forms of the immunoglobulin heavy chain is called a. alternative RNA processing b. isotype switching c. somatic recombination d. somatic hypermutation e. opsonization

alternative RNA processing

IgM and IgD are co-expressed on naive B cells by a process called a. isotype switching b. somatic recombination c. somatic hypermutation d. alternative mRNA splicing e. affinity maturation

alternative mRNA splicing

Which immunoglobulin’s main function is to mediate sensitization of mast cells? a. IgA b. IgD c. IgE d. IgG e. IgM

IgE

Which immunoglobulin is transported most efficiently across mucosal epithelium? a. IgA b. IgD c. IgE d. IgG e. IgM

IgA

\_\_\_\_\_\_\_ forms dimers, whereas _______ forms pentamers. a. IgG; IgD b. IgE; IgM c. IgD; IgM d. IgA; IgM e. IgM; IgG

IgA; IgM

A newborn derives passive immunity from its mother as a result of placental transfer of _____ during pregnancy. a. IgA b. IgD c. IgE d. IgG e. IgM

IgG

\_\_\_\_\_ is secreted into the bloodstream, whereas _____ is secreted into mucus such as gastrointestinal fluid, colostrum, saliva, tears, and sweat. a. monomeric IgM: pentameric IgM b. monomeric IgA: dimeric IgA c. monomeric IgA: dimeric IgG d. monomeric IgA: monomeric IgM e. dimeric IgA: pentameric IgM

monomeric IgA: dimeric IgA

Identify which of the following is not associated with activation-induced cytidine deaminase (AID) activity. a. diversification of the VH domain but not the VL domain b. synthesized in proliferating B cells during active immune responses c. somatic hypermutation d. isotype switching e. conversion of cytosine to uracil

diversification of the VH domain but not the VL domain

The process of _____ results in the amplification of particular B cells with specificity for antigen: a. germline recombination b. somatic recombination c. clonal selection d. antigen processing e. antigen presentation

clonal selection

The antibody transported across mucosal epithelia is \_\_\_\_\_: a. IgA b. IgD c. IgE d. IgG e. IgM

IgA

The third hypervariable region (CDR2) is the most variable site in an immunoglobulin V region. It differs in its composition between the light-chain and heavy-chain V regions. CDR2 of the light chain is composed mainly of the coding joint between the V and J segments, which is formed during somatic recombination, with junctional diversity being generated by the addition of P and N nucleotides. CDR2 of the heavy chain is composed mainly of the D gene segment plus its coding joints with a V gene segment on one side and a J gene segment on the other. P and N nucleotides are also added to these joints during recombination. In addition, the D gene segment sequences differ between immunoglobulins.

False

Identify the correct order of gene segments in a rearranged heavy-chain gene in a naive B cell. 1. La VDJa Cmua Cdelta 2. VDJa Cmua Cdeltaa L 3. La VDJa Cdeltaa Cmu 4. VDJa La Cmua Calpha 1 5. La VDJa Cmua Calpha 1

La VDJa Cmua Cdelta