Chapter 6 Quiz

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. Which of the following is FALSE about antigen processing and presentation via MHC molecules?

Antigen processing and presentation via MHC molecules is driven by the nature and location of the pathogen. correct incorrect

Antigen processing and presentation via MHC molecules is driven by how the peptide antigens are derived. correct incorrect

MHC molecules that present intracellular vs. extracellular peptides differ in their protein structure. correct incorrect

MHC molecules present intracellular and extracellular peptides in a similar manner. correct incorrect

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. Identify the true statement about T-cell receptors.

Each subunit has a constant domain but not a variable domain. correct incorrect

T-cell receptors are composed of two subunits, an α and a β subunit or a γ and a δ subunit. correct incorrect

T-cell receptors have a peptide-binding site that must be able to bind to many different peptides. correct incorrect

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. Which of the following does NOT enhance the diversity of T-cell receptors?

The inclusion of a large number of V, D, and J regions at the loci for T-cell receptor subunits correct incorrect

The random combination of receptor subunits correct incorrect

The junctional diversity driven by recombination. correct incorrect

The lack of possibility of unproductive rearrangements during recombination correct incorrect

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. In the context of rearrangements at T-cell receptor loci, why can somatic recombination result in either a productive or an unproductive rearrangement?

Because rearrangement and the addition and removal of P and N nucleotides is random correct incorrect

Because the α or β loci cannot be eliminated correct incorrect

Because of repackaging of β loci into tightly condensed chromatin correct incorrect

Because of limited number of V, D, and J regions at the loci for T-cell receptor correct incorrect

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. Identify a correct comparison between MHC class I and class II molecules.

The peptide-binding groove of MHC class I molecules contains a single pocket for binding peptides, whereas the groove of class II molecules contains two pockets. correct incorrect

MHC class I molecules present peptides generated by the destruction of intracellular cytosolic proteins, whereas class II molecules present peptides derived through phagocytosis. correct incorrect

Both MHC class I and class II molecules are dissimilar in their three-dimensional structures but similar in composition and the types of peptides they can bind. correct incorrect

The structural features of the peptide-binding groove are provided by α and β chains for class I molecules and by α₁ and α₂ subdomains for class II molecules. correct incorrect

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. Identify the similarity between MHC class I and class II molecules.

Both molecules contain two transmembrane subunits each. correct incorrect

Both molecules accommodate peptides containing 13 to 25 amino acids. correct incorrect

Both molecules possess promiscuous binding specificity. correct incorrect

Both molecules contain peptide-binding grooves formed by the interface of the α and β chains. correct incorrect

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. Identify the prerequisites for T-cell activation.

Interaction of CD8 coreceptor with both MHC class I and class II molecules correct incorrect

Presentation of peptide antigen on the surface of antigen-presenting cells by MHC molecules correct incorrect

Attack on extracellular pathogens by effector T cells correct incorrect

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. Identify the signaling molecules that activate gene transcription leading to cytokine production.

CD4 complex, CD8, and CD4 correct incorrect

CD3 complex and CD19 correct incorrect

CD3 complex, CD28, and CD45 correct incorrect

CD4 complex, CD8, and CD19 correct incorrect

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. Which of the following acts as a signal for the dendritic cell to begin cross-presentation?

Expression of endoplasmic reticulum (ER) chaperones calnexin and calreticulin correct incorrect

Phagocytosis and processing of extracellular antigens correct incorrect

Cytokine release following the activation of engaged CD4 T cells correct incorrect

Presence of self-reactive CD4 T cells correct incorrect

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. Which of the following is true about MHC class I and MHC class II peptide loading?

MHC class II molecules are loaded before they are part of a vesicle capable of fusing with a phagolysosome. correct incorrect

Peptide loading of class I molecules generated from intracellular proteins occurs in the endoplasmic reticulum. correct incorrect

MHC class I peptide loading occurs in four steps. correct incorrect

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. Identify the true statement about MHC alleles.

MHC alleles exhibit codominance in their phenotype. correct incorrect

One of the alleles for any given MHC subunit is an active gene unit. correct incorrect

MHC alleles exhibit dominant or recessive trait characteristics. correct incorrect