Deck 4: Antibody Structure and the Generation of B-Cell Diversity

Question 1

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

A)V_H:C_H
B)V_H:V_L
C)V_L:C_L
D)C_H:C_L
E)V_H:C_L.

Answer 1

B

Question 2

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.

Answer 2

A

Question 3

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.

Answer 3

C

Question 4

Another term commonly used to describe hypervariable loops is

A)multivalency
B)framework regions
C)hinge region
D)complementarity-determining regions
E)signal joint.

Question 5

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.

Question 6

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.

Question 7

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.

Question 8

Which of the following describes two recombination signal sequences required for a permitted somatic recombination event?

A)V_H 7-12-9::9-23-7 J_H
B)V_λ7-23-9::9-23-7 J_λ
C)D_H 7-12-9::9-23-7 JH
D)V_κ7-12-9::7-23-9 J_κ
E)V_H 9-23-7::7-12-9 D_H.

Question 9

of the following comprise heavy-chain isotypes of immunoglobulin except

A)α
B)β
C)γ
D)δ
E)ε

Question 10

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.

Question 11

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.

Question 12

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.

Question 13

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.

Question 14

_______ 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.

Question 15

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.

Question 16

Describe the structure of an antibody molecule and how this structure enables it to bind to a specific antigen.Include the following terms in your description: heavy chain (H chain),light chain (L chain),variable region,constant region,Fab,Fc,antigen-binding site,hypervariable region,and framework region.

Question 17

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.

Question 18

_____,_____,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.

Question 19

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.

Question 20

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.

Question 21

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).

Question 22

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.

Question 23

would be the effect of a genetic defect that resulted in a lack of somatic recombination between V,D,and J segments?

Question 24

do recombination signal sequences ensure that gene segment rearrangement occurs in the right order?

Question 25

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.

Question 26

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.

Question 27

Explain why catalytic antibodies are attracting attention in the medical field.
B.Provide two potential examples.

Question 28

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.

Question 29

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.

Question 30

is additional diversity introduced into the variable region by the molecular mechanism of somatic recombination? Include the following terms in your

Question 31

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.

Question 32

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.

Question 33

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.

Question 34

What is the basic structural difference between the immunoglobulins produced by B cells and their descendants before antigen encounter and after antigen encounter?
B.Say which cell type(s)produce each form.
C.In which way do these different molecular forms resemble each other?

Question 35

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.

Question 36

Explain briefly how a vast number of immunoglobulins of different antigen specificities can be produced from the relatively small number of immunoglobulin genes present in the genome.Include the following terms in your explanation: somatic recombination; germline configuration; V,D,and J segments.
B.What is the final arrangement of gene segments in the rearranged immunoglobulin heavy-chain gene V region,and in what order do these gene segment rearrangements occur?
C.In what order do the various immunoglobulin loci rearrange?

Question 37

What is an epitope?
B.Define the term multivalent antigen.
C.How does a linear epitope differ from a conformational epitope?
D.Do antibodies bind their antigens via noncovalent bonding or via covalent bonding?

Question 38

_____ 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.

Question 39

Explain how mature,naive B cells co-express IgM and IgD.

Question 40

highest degree of diversity resulting from somatic recombination is concentrated ____________ of the V_H and V_L 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 V_H and V_L 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.

Question 41

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.

Question 42

Identify the correct order of gene segments in a rearranged heavy-chain gene in a naive B cell.

A)L-VDJ-C_μ-C_δ
B)VDJ-C_μ-C_δ-L
C)L-VDJ-C_δ-C_μ
D)VDJ-L-C_μ-C_α1
E)L-VDJ-C_μ-C_α1.

Question 43

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).

Question 44

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.

Question 45

What are the functions of the Igα and Igβ proteins?
B.Explain why it is desirable that they do not vary in sequence from cell to cell in the same way that immunoglobulins do.

Question 46

third hypervariable region (CDR3)is the most variable site in an immunoglobulin V region.It differs in its composition between the light-chain and heavy-chain V regions.Explain what this difference is and how the diversity in CDR3 is generated.

Question 48

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.

Question 49

Describe the process responsible for altering the expression of membrane-bound immunoglobulin to secreted antibody.

Question 50

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.

Question 51

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.

Question 52

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.

Question 53

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.

Question 54

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.

Question 55

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

Question 56

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.

Question 57

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).

Question 58

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.

Question 59

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.

Question 60

What is affinity maturation and what molecular process enables it to occur?
B.Describe this process and its consequences.

Question 61

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.

Question 62

_______ forms dimers,whereas _______ forms pentamers.

A)IgG; IgD
B)IgE; IgM
C)IgD; IgM
D)IgA; IgM
E)IgM; IgG.

Question 63

Which immunoglobulin's main function is to mediate sensitization of mast cells?

A)IgA
B)IgD
C)IgE
D)IgG
E)IgM.

Question 64

Influenza virus contains two proteins,called hemagglutinin and neuraminidase,exposed on the surface of the virion.Two additional proteins,located on the interior of the virion,are called matrix protein and nucleoprotein.Which of these four proteins will generate a better antibody response and why?

Question 65

Identify the four types of antibody used for therapeutic purposes.
B.How is each produced?
C.(i)Which is most desirable for the treatment of chronic conditions? (ii)Why? (iii)Provide an example.

Question 66

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.

Question 67

Which immunoglobulin isotypes (out of IgM,IgG1,IgG2,IgG3,IgG4,IgA,IgE,and IgD)participate in (a)neutralization; (b)opsonization; (c)sensitization for killing by NK cells; (d)sensitization of mast cells; (e)activation of complement? Which isotypes (f)are transported across epithelium; (g)are transported across the placenta; (h)diffuse into extravascular sites?

Question 68

Monoclonal antibodies are used for a wide range of applications including serological assays and diagnostics probes in the laboratory,and as therapeutic reagents in the clinic.Discuss why 'humanizing' monoclonal antibodies is necessary for use as therapeutic reagents but is not necessary when monoclonal antibodies are used as serological or diagnostic reagents.

Question 69

Which immunoglobulin is transported most efficiently across mucosal epithelium?

A)IgA
B)IgD
C)IgE
D)IgG
E)IgM.

Question 70

What is the difference between polyclonal antibodies and monoclonal antibodies?
B.How is each produced?

Question 71

_____ 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.

Question 72

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.

Question 73

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.

Question 74

Isotype switching and immunoglobulin gene rearrangement by somatic recombination are both recombinational processes but have very different outcomes.Give four ways in which they differ from each other.

Question 75

would be the effect of a genetic defect that resulted in a lack of recombination between the switch regions in the immunoglobulin C-region genes?

Question 76

What is isotype switching?
B.Explain the molecular mechanism of isotype switching.
C.Why is isotype switching important?

Question 77

antibody transported across mucosal epithelia is _____:

A)IgA
B)IgD
C)IgE
D)IgG
E)IgM.
ANSWERS