Exam 2 Flashcards
With the exception of B cells, all other cells of the body have the immunoglobulin genes in the ______________.
Germline configuration
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?
The portion that makes physical contact with the ligand comprises Vbeta and Cbeta, the domains farthest from the T-cell membrane.
The mutational mechanism that results in the production of antibodies that bind antigen with higher affinity is called _____.
Somatic hypermutation
Unlike the C regions of immunoglobulin heavy-chain loci, the C regions of the T-cell receptor beta-chain loci ______.
Are functionally similar
On the heavy-chain immunoglobulin gene locus, recombination signal sequences flank _______ of the V segment, _______ of the D segment, and _______ of the J segment.
The 3-prime side; both sides; the 5-prime side
Which of the following cell types is(are) not considered a professional antigen-presenting cell(s)?
Neutrophil
The name given to a fully activated and differentiated B cell that secretes antibody is __________________.
Plasma cell
In what way does the kappa light chain differ from the lambda light chain?
The kappa locus encodes a single C segment, whereas the lambda locus has more than one
The role of the CD3 proteins and zeta chain on the surface of the cell is to ___________________.
Transduce signals to the interior of the T-cell
Which of the following describes the sequence of events involved in the processing of peptides that will be presented as antigen with MHC class II?
endocytosis -> protease activity -> removal of CLIP from MHC class II -> binding of peptide to MHC class II -> plasma membrane
CD8 T-cell subpopulations are specialized to combat _______ pathogens, whereas CD4 T-cell subpopulations are specialized to combat _______ pathogens.
Intracellular; extracellular
Directional selection is best described as ____________.
selected alleles increase in frequency in a population
A circulating B cell that has never before encountered antigen expresses _____ on the cell surface.
IgM and IgD
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
Which of the following determines the isotype of an immunoglobulin?
Its heavy chain
All of the following processes occur in mature B cells after antigen encounter except:
Somatic recombination
Which of the following does not describe B-cell receptors?
B-cell receptors lack specificity and can bind to a number of different antigens.
T-cell receptors interact not only with peptide anchored in the peptide-binding groove of MHC molecules, but also with ____________________.
variable amino acid residues on alpha helices of the MHC molecule
Which of the following is/are not encoded on chromosome 6 in the HLA complex?
beta2-microglobulin and invariant chain
Peptides that bind to a particular MHC isoform usually have either the same or chemically similar amino acids at two to three key positions that hold the peptide tightly in the peptide-binding groove of the MHC molecule. These amino acids are called _____ and the combination of these key residues is known as its _________________.
anchor residues; peptide-binding motif
Which of the following characteristics is common to both T-cell receptors and immunoglobulins?
Somatic recombination of V, D, and J segments is responsible for the diversity of antigen-binding sites.
MHC class II molecules are made up of two chains called _______, whose function is to bind peptides and present them to _______ T cells.
alpha and beta; CD4
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 _______.
Affinity maturation
Which of the following can be found in serum in a monovalent form?
IgG4
Which of the following best describes the function of tapasin?
Tapasin is a bridging protein that binds to both TAP and MHC class I molecules and facilitates the selection of peptides that bind tightly to MHC class I molecules.
Which of the following statements regarding CD8 T cells is incorrect?
When activated, CD8 T cells in turn activate B cells.
The CDR3 loops of the T-cell receptor contact the _______.
side chains of amino acids in the middle of the peptide
The enzyme responsible for adding N nucleotides is _______.
terminal deoxynucleotidyl transferase
Which of the following is not a characteristic of immunoproteasomes?
They produce a higher proportion of peptides containing acidic amino acids at the carboxy terminus compared with constitutive proteasomes.
Which of the following describes two recombination signal sequences required for a permitted somatic recombination event?
DH 7-12-9::9-23-7 JH
A newborn derives passive immunity from its mother as a result of placental transfer of _____ during pregnancy.
IgG
How many complementarity-determining regions contribute to the antigen-binding site in an intact T-cell receptor?
6
Naive B cells are recognized by their expression of ______________.
both IgM and IgD on the cell surface
Which of the following is not a term used to describe the molecules or components of molecules to which antibodies bind?
CDR loops
Which of the following is mismatched?
four C domains: IgM and IgD
In reference to the interaction between T-cell receptors and their corresponding ligands, which of the following statements is correct?
The most variable part of the T-cell receptor is composed of the CDR3 loops of both the alpha and beta chains.
_____, _____, and _____ are the three most abundant antibodies in blood:
IgA, IgG, and IgM
Which of the following statements regarding Omenn syndrome is incorrect?
It is the consequence of complete loss of RAG function.
Which of the following is not a characteristic of native antigen recognized by T cells?
not requiring degradation for recognition
Another term commonly used to describe hypervariable loops is ___________.
complementarity-determining regions (CDRs)
Which of the following is matched incorrectly?
affinity maturation: addition of P and N nucleotides
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 ____________.
in CDR3; throughout the V region
Which immunoglobulin is transported most efficiently across mucosal epithelium?
IgA
The immunological consequence of severe combined immunodeficiency disease (SCID) caused by a genetic defect in either RAG-1 or RAG-2 genes is _____________________.
lack of somatic recombination in T-cell receptor and immunoglobulin gene loci
T cells recognize antigen when the antigen ___________________.
forms a complex with membrane-bound MHC molecules on another host-derived cell
Which of the following describes a typical ligand for an alpha:beta T-cell receptor?
peptide:MHC complex
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.
C regions
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
IgG possesses _______ binding sites for antigen, and the T-cell receptor possesses _______ binding sites for antigen.
2; 1
All of the following are oligomorphic except ___________________.
HLA-DQ beta chain
