Deck 3: Recognition and Response

Question 1

Which of the following types of bonds would be LEAST likely in a receptor-ligand interaction?

A)Ionic bond
B)Covalent bond
C)Hydrogen bond
D)Hydrophobic interaction
E)All of the answers are equally likely.

Answer 1

B

Question 2

The end results of signal transduction are varied but can include

A)Induction of cell division.
B)Cellular differentiation.
C)Altered metabolism.
D)Altered protein secretion patterns.
E)All of the answers are correct.

Answer 2

E

Question 3

K_a, the association constant, is a measure of which of the following?

A)The concentration of unbound ligand
B)The concentration of unbound receptor
C)The affinity of receptor for ligand
D)The size of the receptor relative to the ligand
E)The number of ligands for each receptor

Answer 3

C

Question 4

Which of the provided disassociation constants is MOST likely to be observed from an antibody binding an antigen during an immune response involving memory B cells?

A)10^-3 M
B)10^-5 M
C)10^-2 M
D)10^-10 M
E)Antibody-antigen interactions cannot be measured.

Question 5

Receptors that are multivalent tend to bind to their ligands more strongly than receptors with a single binding site.What is the term used to describe this phenomenon?

A)Avidity
B)Valency
C)Affinity
D)Magnetism
E)None of the answers are correct.

Question 6

Which of the following BEST describes how cytokines are released from activated T cells?

A)Cytokines are released near where T-cell receptors are clustered.
B)T cells release cytokines on the side of the cell opposite the MTOC to more efficiently distribute the response around the cell.
C)T cells release cytokines evenly around the cell.
D)Cytokines are released in short bursts from preformed vesicles full of cytokines.
E)Cytokines are released in whatever direction the MTOC happens to be facing upon TCR ligation.

Question 7

Receptors that dimerize upon ligand binding often contain _____ in their cytoplasmic domains.

A)tyrosine kinases
B)hydrophobic regions
C)proteases
D)metal-binding regions
E)large immunoglobulin folds

Question 8

Portions of the cytoplasmic domains of many immune receptors are targets for phosphorylation.These domains are known as

A)Grb domains.
B)ITAMs.
C)leucine zipper motifs.
D)SOS domains.
E)None of the answers are correct.

Question 9

You note a population of T cells that contain primarily high-affinity IL-2R on their cell surfaces.Based on that observation, what can you predict about the activation state of the cells?

A)They have not been exposed to antigen.
B)T cells do not express IL-2R, so we cannot determine their activation state using these data.
C)This cell population has been exposed to IL-2 and is active.
D)They have been exposed to antigen but not IL-2.
E)None of the answers are correct.

Question 10

Lipid rafts are highly ordered regions of the cell membrane that are enriched in

A)unsaturated fats.
B)cholesterol.
C)metabolic proteins.
D)clathrin.
E)tubulin.

Question 11

Which of the following are well-established ways that tyrosine phosphorylation directly affects signaling pathways?

A)Inducing kinase activity
B)Recruiting enzymes through SH2 domains
C)Opening calcium channels
D)Both inducing kinase activity and recruiting enzymes through SH2 domains
E)Both recruiting enzymes through SH2 domains and opening calcium channels

Question 12

Which of the following is the CORRECT relationship?

A)PIP₂ = PIP₃ - DAG
B)PIP₂ = IP₃ + DAG
C)PLC = PIP₂ + PIP₃
D)DAG = PIP₂ + PIP₃
E)PIP₃ = IP₃ + PIP₂

Question 13

Which transcription factor becomes translocated to the nucleus downstream of calmodulin activation?

A)NF- ? B
B)NFAT
C)STAT1
D)STAT2
E)STAT3

Question 14

G proteins

A)bind GTP.
B)dephosphrylate ITAMs.
C)are transcription factors.
D)downmodulate immune responses.
E)are adhesion molecules.

Question 15

Which of the following is responsible for IL-2 expression in T cells?

A)NF- ? B
B)NFAT
C)AP-1
D)Both NF- ? B and NFAT are responsible
E)All of the answers are responsible.

Question 16

Immunoglobulin domains consist of

A)a series of ? helices bound together by hydrophobic interactions in their side chains.
B) ? helices alternating with parallel ? -pleated sheets.
C)Antiparalle ? l -pleated sheets folded and stabilized by hydrophobic interactions.
D)Compact ? -parallel sheets forming a barrel structure.
E) ?
Helices held together by leucine repeats.

Question 17

On the gel below, which bands would you expect to bind antigen?
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A)B and A
B)B and B
C)B and C
D)B and D
E)B and A, B, and C

Question 18

Antibodies consist of

A)two identical heavy chains and two identical light chains.
B)an ? chain, a ? chain, a . ? chain, and a ? chain
C)two ? chains, an . ? chain, and a ? chain
D)two ? chains, an . ? chain, and a ? chain
E)either an ? chain or a a ? chain, a ? chain, and a ? chain.

Question 19

Which of the following isotypes of antibodies is the largest?

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

Question 20

An antibody's idiotype refers to

A)the kind of Fc region it contains.
B)the sequence of its CDR.
C)Ii's allelic form.
D)whether it is membrane bound or secreted.
E)which accessory molecules associate with it.

Question 21

Carbohydrate chains attached to the C_H2 domains of IgA, IgD, and IgG are believed to

A)allow for closer contact between partner chains.
B)confer stability to the molecule resulting in a higher desaturation temperature.
C)prevent protease degradation.
D)provide space for complement protein binding.
E)increase binding affinity for antigen.

Question 22

Whether an immunoglobulin is secreted or membrane bound is directly determined by

A)the sequence of the DNA in the Ig locus.
B)mRNA splicing.
C)the kind of B cell that is producing it.
D)DNA rearrangement.
E)GPI anchors.

Question 23

Receptors that bind the constant regions of antibodies are known as

A)B-cell receptors.
B)T-cell receptors.
C)idiotype receptors.
D)toll-like receptors.
E)Fc receptors.

Question 24

Large amounts of monoclonal antibodies in the serum of an individual might be an indicator of

A)infection.
B)T-cell deficiency.
C)autoimmune disease.
D)myeloma.
E)stress.

Question 25

Which of the following would be BEST for depleting an entire class of antibodies?

A)Anti-idiotype antibody
B)Anti-isotype antibodies
C)Anti-CD19
D)Anti-CD4
E)Anti-CD8

Question 26

Which of the following BEST describes why it is challenging for surface immunoglobulin to transduce a signal into the cell upon antigen binding?

A)It takes twice as much antigen to stimulate the cells because each antibody has two antigen binding sites.
B)The cytoplasmic domain of surface Ig only has three amino acids.
C)Ig ? is rapidly dephosphorylated.
D)Ig is an inflexible molecule.
E)All of the answers are correct.

Question 27

Regions of TCRs and BCRs that are particularly variable in their amino acid sequences are known for

A)binding to antigen.
B)sticking to denatured proteins.
C)spanning the plasma membrane.
D)binding to adaptor proteins.
E)becoming phosphorylated.

Question 28

Which of the following contains the MOST ITAMs?

A)CD3 ?
B)CD3 ?
C)CD3 ?
D)TCR ?
E)TCR ?

Question 29

CD4 binds to

A)TCR . ?
B)TCR . ?
C)MHC class I.
D)MHC class II.
E)CD8.

Question 30

The antigen specific component of the B-cell receptor is

A)ITAM.
B)CD19.
C)Ig ? / . ?
D)CD21.
E)Lyn.

Question 31

In the research laboratory, you observe that B cells, cytotoxic T cells and mast cells begin to proliferate when exposed to IL-4.In this case, this effect of IL-4 may be described as

A)synergy.
B)antagonism.
C)redundancy.
D)pleiotrophy.
E)both redundancy and pleiotrophy.

Question 32

The biological outcomes of immune system recognition can include

A)migration of leukocytes into infected tissues.
B)clearance of a pathogen by an activated macrophage.
C)promotion of optimal antigen presentation.
D)induction of long-lived B and T cells.
E)All of the answers are correct.

Question 33

Name the two key elements to a meaningful receptor-ligand interaction as a means of cell-to-cell communication.

Question 34

Explain the observation that receptor-ligand interactions are noncovalent despite the weak nature of such bonds versus covalent bonds.

Question 35

In your own words, explain an advantage of a bivalent versus univalent approach to receptor-ligand binding.

Question 36

Structural studies of a potentially new cell surface protein reveal a hydrophobic C-terminal region, several regions consisting of sheets, predicted disulfide bonds, and a variable N-terminal area dominated by loops.Based on this information, what family of proteins might this protein belong to? What is a potential function of the hydrophobic C-terminal region?

Question 37

Imagine you are observing, at the molecular scale, interactions that occur when a dendritic cell activates a naïve CD4⁺ T cell.If the dendritic cell were exposed to an agent that disrupts the microtubule portion of the cytoskeleton prior to interaction, what would be the impact on T-cell activation?

Question 38

Compare the locations of the antigen receptors of innate versus adaptive immunity.Which has the GREATEST variety?

Question 39

The B-cell receptor has structural and functional elements.How would you describe the B-cell receptor from both a structural and functional perspective?

Question 40

Three different class 1 cytokine receptor chains bind the same chain to form functional cellular receptors.Are there advantages to this type of "mixing and matching" of protein chains?

Question 41

Can you think of a functional property of chemokines that allows them to induce the directed movement of leukocytes to a site of inflammation from the circulation?

Question 42

Consider the following statement: Activated macrophages cannot clear pathogens without activating adaptive immunity.Is the statement true or false? Justify your answer.