Immunology Block 2 Exam Questions with 100% Correct Answers Latest Version 2024 Verified
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_______ greatly activates the classical pathway of complement activation - IgM
_______ is expressed by T cells whose function is to activate other cells. - CD4
___________ is expressed by cytotoxic T cells - CD8
____________ molecules present peptides from pathogens, commonly viruses, to CD8 T c...
Immunology Block 2 Exam Questions
with 100% Correct Answers | Latest
Version 2024 | Verified
_______ greatly activates the classical pathway of complement activation - ✔✔IgM
_______ is expressed by T cells whose function is to activate other cells. - ✔✔CD4
___________ is expressed by cytotoxic T cells - ✔✔CD8
____________ molecules present peptides from pathogens, commonly viruses, to CD8 T cells, which are
specialized to kill any cell that they specifically recognize. - ✔✔MHC class I
_____________ increases the expression of both MHC Class I and MHC Class II molecules, and can
induce the expression of MHC Class II molecules on certain cell types that do not normally express them
- ✔✔IFN-Gamma
______________ dendritic cells are thought to act as sentinels in early defense against viral infection on
the basis of their expression of TLRs and the intracellular nucleic acid-sensing RIG-I-like helicases, and
their high production of antiviral type I interferons. - ✔✔Plasmacytoid
A mutagenesis screen performed on mice identified a gene with an important function in B cells.
Analysis of B cells from the spleens of these mutant mice showed the results shown in Figure Q5.23A.
However, when the C coding sequences were determined, no mutations in these DNA sequences were
found. To study this further, genetic crosses were set-up with another mouse strain carrying an allelic
variant of the immunoglobulin heavy chain locus. The original mutant mouse strain (strain A) carries
IgMa and IgDa alleles of these heavy chain genes. The second mouse strain (strain B) carries the IgMb
and IgDb alleles of the heavy chain genes. These two parental strains were crossed together, generating
progeny that were all heterozygous for IgM and IgD alleles (i.e., all progeny are IgMa/b and IgDa/b).
These heterozygous progeny represent the F1 generation. Brother/sister matings of F1 mice generate F2
progeny. These F2 mice - ✔✔The gene for a factor required for alternative mRNA splicing of the
immunoglobulin heavy chain primary mRNA transcript
,Alleles for MHC genes have ___________ expression, meaning that the product (polypeptide) of both
parental genes are expressed on the cell surface. - ✔✔co-dominant
Amino acid sequence analysis of all of the peptides found in a single IgG antibody would reveal unique
peptide sequences totaling ~600-700 amino acids. Using this estimate, the predicted molecular weight
of an antibody protein would be ~70-75 kDa. Yet, an intact antibody protein has a molecular weight of
~150 kDa. The explanation for this discrepancy is: - ✔✔Each IgG antibody is a complex of two identical
light chains and two identical heavy chains.
An activated cytotoxic T cell can kill any virus-infected target cell, including those that do not express co-
stimulatory molecules. - ✔✔true
An adaptive immune response is initiated when a pathogen surmounts innate defense mechanisms. -
✔✔true
Antibodies that bind with high affinity to some viral surface proteins require heavy chain CDR3 loops of
unusual length. Whereas the average human heavy chain CDR3 length is ~15 amino acids, antibodies
with VH CDR3 loops of >30 amino acids are readily detected in the repertoire. These antibody heavy
chains with CDR3 lengths of >30 amino acids would likely be missing in individuals lacking: - ✔✔Terminal
deoxy nucleotidyl transferase (TdT)
Antibody binding to a pathogen surface is greatly enhanced when both antigen-binding sites of the
antibody are engaged at once, a feature known as bivalent binding. It is possible for antibodies to bind
bivalently to a wide variety of components on many different pathogen surfaces due to the flexibility in
the protein at the hinge region and at the V-C junction. - ✔✔true
Antibody diversity is generated by multiple mechanisms, each of which contributes to the generation of
antibodies with up to 1011 different amino acid sequences in their antigen-binding sites. Several of these
mechanisms involve changes in the DNA sequences encoding the antibody heavy and light chain
proteins. One mechanism that does not rely on changes to the DNA within the immunoglobulin heavy
and light chain gene loci is, instead, dependent on: - ✔✔The contributions of amino acids from both the
heavy chain and the light chain to form the antigen-binding site
Antibody heavy and light chain polypeptides consist of repeated domains, each of which is ~110 amino
acids and folds up into a compact threedimensional structure known as an 'immunoglobulin domain.'
, These immunoglobulin domains are: - ✔✔Similar but not identical in amino acid sequence when
comparing the domains in a single heavy chain polypeptide
At early timepoints following an infection, examination of lymph node CD4 T cells responding to the
pathogen would show a heterogeneous population of cells representing several different effector
lineages. Likewise, the cytokines produced by these cells would include IFNgamma, IL-4, and possibly
others. However, approximately one week later at the peak of the T cell response, the pathogen-specific
CD4 T cell population would be largely homogeneous in their production of a single effector subset
cytokine profile. This change comes about due to: - ✔✔Enhanced differentiation of newly activated CD4
T cells into one effector subset
B cells also serve as antigen-presenting cells by processing antigens and displaying them via
___________________. - ✔✔MHC 2 molecules
B-cell receptors and T-cell receptors share a mechanism for generating diversity, and also share overall
structural homology both in their V domains and their C domains. This is because the two proteins have
nearly identical functions in the immune responses mediated by their respective cell types. - ✔✔false
Both MHC class I and MHC class II molecules are highly polymorphic genes in the human population,
with tens to hundreds of different alleles co-existing in the population. This means that a comparison of
the MHC protein sequences between two individuals would reveal amino acid differences between one
individual and the next. However, these amino acid differences are not randomly distributed along the
entire protein, but are clustered in certain locations. The diagram in Figure Q4.16 that most correctly
indicates the regions of greatest variability between different MHC proteins (shown by the red
highlights) is: - ✔✔C
Cells that secrete antibodies are called: - ✔✔B cell derived plasma cells
Classical MHC molecules function as peptide-binding receptors that present these peptides to alpha:beta
T cells for recognition by alpha:beta T-cell receptors. MHC molecules can be detected as far back in
evolution as sharks, the same time at which Tcell receptors can be identified. Examination of shark MHC
proteins indicates that these molecules likely function identically to human MHC molecules. This
conclusion is based on: - ✔✔The conservation of amino acid residues important in peptide binding in
both shark and human MHC proteins
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