Cell Bio Quiz 8

Which of the following is not associated with cell-cell adhesions? A. Collagen B. Desmosome C. Gap junction D. Tight junction

A. Collagen

Which of the following cell surface specializations involves both cadherin membrane proteins and intermediate filaments? A. Desmosomes B. Focal contacts (focal adhesions) C. Hemidesmosomes D. Tight junctions

A. Desmosomes

Which of the following types of adhesion best describes cadherin function at sites of cell-cell contact? A. Homophilic adhesion B. Lectin binding to carbohydrate C. Heterophilicadhesion D. Hemidesmosome binding to the basement membrane

A. Homophilic adhesion

Member of a family of cell-surface carbohydrate-binding proteins that mediate transient, Ca2+ - dependent cell-cell adhesion in the bloodstream, for example between white blood cells and the endothelium of the blood vessel wall. A. Selectins B. Cadherins C. Connexins D. Integrins

A. Selectins

Each of the following statements about cadherins is true EXCEPT: A. Adhesion is Ca2+-dependent and homophilic. B. Cadherins interact with components of the basement membrane. C. Cadherins associate with the actin cytoskeleton. D. When mixed together, cells expressing different cadherins sort out into homotypic cell aggregates.

B. Cadherins interact with components of the basement membrane.

Focal adhesions are dynamic structures that contain integrins attached to the cytoskeleton and the extracellular matrix protein fibronectin. Which of the following functions are attributed to the dynamic nature of focal adhesions? A. Cell detachment from the extracellular matrix (substrate) B. Cell migration (locomotion) C. Exocytosis D. Phagocytosis

B. Cell migration (locomotion)

Which cellular junctions mediate direct attachment of the cytoskeletons between adjacent cells A. Intercalated discs B. Desmosomes C. Gap junctions D. Tight junctions

B. Desmosomes

Which type of cell junction would be adversely affected by a disorder resulting in functionally defective integrins? A. Desmosome B. Focal adhesions C. Tight junction D. Gap junction

B. Focal adhesions

Action potential propagation in cardiac cells is important for the proper function of the heart. Which of the following intercellular connections will be most effective in cardiac cells? A. Gap junctions - they facilitate exchange of fluid between cells. B. Gap junctions - they facilitate exchange of ions between cells. C. Tight junctions - they facilitate exchange of ions between cells. D. Tight junctions - they facilitate exchange of fluid between cells.

B. Gap junctions - they facilitate exchange of ions between cells.

Which of the following classes of junctions would be adversely affected in a disease that reduced integrin gene expression in an epithelium? A. Tight junctions B. Hemidesmosomes C. Adherens junctions D. Gap junctions

B. Hemidesmosomes

In patients with leukocyte adhesion deficiency (LAD), which of the following cells are conspicuously absent from sites of infection? A. Mastcells B. Neutrophils C. Plasmacells D. Eosinophils

B. Neutrophils

A researcher is analyzing an autoimmune disease. The results indicate that the patient has antibodies targeting occluding proteins. Which of the following is likely to be true for the patient? A. The patient's cadherins are also targeted B. There is an easy passage of molecules through the space between adjacent cells C. Cell junctions that require actin will be disrupted D. The patient will lack adherens junctions.

B. There is an easy passage of molecules through the space between adjacent cells

Which of the following is NOT a property of integrins? A. They are transmembrane proteins. B. They exist in the membrane as homodimers. C. They bind to extracellular matrix glycoproteins. D. They are mechanically linked to the actin cytoskeleton.

B. They exist in the membrane as homodimers.

Tight junctions have which of the following characteristics? A. They function in intercellular communication B. They function as a permeability barrier C. Theyanchorcellstothebasallamina D. They give strength to the epidermis of the skin so that it can resist abrasion

B. They function as a permeability barrier

Which of the following statements about tight junctions is correct? A. They allow for intercellular communication B. They maintain the distinct composition of plasma membrane domains. C. They are associated with cadherin molecules D. They bind to proteins in the basal lamina

B. They maintain the distinct composition of plasma membrane domains.

Zona occludens are formed at _____________ junctions and desmosomes are formed at ___________ junctions A. cell-cell, cell-matrix B. cell-cell, cell-cell C. cell-matrix, cell-cell D. cell-matrix, cell-matrix

B. cell-cell, cell-cell

A calcium-dependent cell adhesion molecule found at desmosomes is: A. Catenin B. N-CAM C. Cadherin D. Integrin

C. Cadherin

Several contiguous epithelial cells are labeled by injection of a small molecular weight fluorescent dye into the cytosol; this dye cannot cross the lipid bilayer of membranes. One cell is experimentally bleached with laser light to destroy the dye, but it soon recovers its fluorescence. This recovery is best explained by the function of which of the following structures? A. Basal lamina B. Desmosomes C. Gap junctions D. Tight junctions

C. Gap junctions

Integrin binding to I-CAM (IgSF member) is best categorized as an example of which of the following types of adhesion? A. Homophilic B. Lectin-carbohydrate C. Heterophilic D. Junctional

C. Heterophilic

Which of the following is true of the integrins? A. Each member of the family recognizes only a single ECM protein. B. All integrins are involved in the cell-ECM adhesion. C. Integrin binding of ECM can stimulate cell-signaling pathways that regulate cell growth, survival and gene expression. D. Integrins are a major component of the zonula adherens junctions.

C. Integrin binding of ECM can stimulate cell-signaling pathways that regulate cell growth, survival and gene expression.

Which statement BEST describes tight junctions? A. The main function of the tight junction is for cell-to-cell communication B. The main function of the tight junction is for cell-to-cell adhesion C. The main function of the tight junction is to provide an occluding barrier to free movement of materials across an epithelium D. Tight junctions tether epithelial cells to the underlying basement membrane

C. The main function of the tight junction is to provide an occluding barrier to free

Which of the following statements about desmosomes is true? A. They are the portion of the junctional complex that is closest to the lumen B. They function as a diffusion barrier C. They are associated with intermediate filaments D. Connexin membrane proteins contribute to their structure

C. They are associated with intermediate filaments

Desmosomes provide structural integrity to tissues that undergo severe mechanical stress. What characteristic of these junctional structures provides the mechanical stability that many tissues require? A. They anchor intermediate filaments in a cell to the extracellular matrix. B. They form interconnected strands of connection of one cell to another cell. C. They link intermediate filaments of the cytoskeleton in one cell to those in another cell. D. They are composed of desmoglein and desmocollin that link the plasma membrane of one cell to that of an adjoining cell.

C. They link intermediate filaments of the cytoskeleton in one cell to those in another cell.

The association of actin filaments with which of the following junctions gives mechanical stability to the apical end of columnar epithelial cells? A. desmosomes (maculaeadherens) B. tight junctions (zonulae occludentes) C. adherens junctions (zonula adherens) D. gap junctions

C. adherens junctions (zonula adherens)

Each of the following is true of both cadherins and integrins EXCEPT A. both are transmembrane glycoproteins B. both can associate with the actin cytoskeleton C. both may be found in zonula adherens junctions D. both represent gene families

C. both may be found in zonula adherens junctions

Malignant melanoma cells arise from melanocytes, pigment-producing cells that normally reside in the basal layer of the epidermis (skin). Progression to highly invasive metastatic cancer involves a number of steps that involve changes in cell adhesion. Which of the following changes are most likely to precede the initial release of a melanoma cell from the epidermis? A. increased cell adhesion to the basement membrane B. increased cell-cell adhesion and decreased cell adhesion to the basement membrane C. decreased cell-cell adhesion and decreased adhesion to the basement membrane D. increased cell-cell adhesion

C. decreased cell-cell adhesion and decreased adhesion to the basement membrane

Some extracellular matrix (ECM) molecules are able to function in cell-cell adhesion by acting as an "intermediate linker" between cells. Which of the following statements is most likely to be a common feature of any individual ECM molecule capable of linking adjacent cells to one another? A. contains glycosaminoglycan side chains B. uses a lectin domain to bind to cell-surface adhesion molecules C. has multiple binding sites for cell-surface adhesion molecules D. binds to cadherins

C. has multiple binding sites for cell-surface adhesion molecules

The key components of desmosomes are cadherins and __________. A. actin B. microfilaments C. intermediate filaments D. microtubules

C. intermediate filaments

Besides the plasma membranes of its cells, which one of the following features of columnar epithelium is primarily responsible for its function as a permeability barrier? A. desmosomes (macula adherens) B. adherens junction C. tight junction (zonula occludens) D. basal lamina

C. tight junction (zonula occludens)

Type of anchoring junction that links intermediate filaments in two adjoining cells. A. Tight junction B. Gap junction C. Hemidesmosome D. Desmosome

D. Desmosome

A defect in which of the following types of junctions is likely to result in an epithelium that is no longer tightly adherent to the basement membrane? A. Gap junction B. Tight junction C. Adherens junction D. Hemidesmosome

D. Hemidesmosome

A patient is found to have a defect in his intermediate filaments. Which of the following cellular junctions will be absent in this patient? I. Desmosomes II. Gap junctions III. Hemidesmosomes A. I, II, III B. I and II C. All three junction types will be present in the patient D. I and III

D. I and III

In the ECM, fibronectin is a ligand of a particular adhesion molecule. Therefore, that adhesion molecule most likely belongs to which family? A. Cadherins B. Collagens C. Immunoglobulin superfamily D. Integrins

D. Integrins

Which of the following processes is required in order for neutrophil rolling to occur in response to inflammatory signals? A. Recognition of endothelial cell fibronectin by integrins on the neutrophil surface. B. Integrin dependent binding of the neutrophiltoI-CAM under flow conditions. C. Arrest and extra vasation of the neutrophil under flow conditions. D. P-selectin dependent binding of the neutrophil to the end othelium under flow conditions

D. P-selectin dependent binding of the neutrophil to the end othelium under flow conditions

What is the main function of a tight junction? A. Regulates adhesion of epithelial cells to the basement membrane. B. Anchors the plasma membrane to the cytoskeleton and redistributes membrane proteins between plasma membrane domains. C. Provides mechanical support for the cells of the epithelium. D. Restricts paracellular transport, segregates plasma membrane proteins in domains (e.g., apical, basolateral)

D. Restricts paracellular transport, segregates plasma membrane proteins in domains (e.g., apical, basolateral)pi aa

Which of the following properties is unique to cell adhesion mediated by selectins? A. Selectins are transmembrane proteins; other adhesion molecules are intracellular. B. Selectins mediate cell-to-matrix adhesion, not cell-to-cell adhesions. C. Selectins have homophilic binding, with other selectins serving as their ligands. D. Selectins on one cell bind to the glycosylated ligands on another cell.

D. Selectins on one cell bind to the glycosylated ligands on another cell.

A researcher notices a connection between two cells. Upon analyses, he concludes that there is no exchange of water or ions between cells. Which of the following could be the identity of the connections between the two cells? A. Desmosomes B. Gap junctions C. Hemidesmosomes D. Tight junction

D. Tight junction

Monocytes (precursors of neutrophils) are attracted to a site of inflammation. The directed motion is accomplished by the expression of selectins expressed by the monocytes and the endothelial cells lining the blood vessel. Once at the site of damage, the monocyte leaves the blood vessel and enters the tissues (extravasation). Which of the following cell junctions would block best the movement of the monocyte from the vessel into the tissue? A. Adherens junctions B. Hemidesmosomes C. Gapjunctions D. Tight junctions

D. Tight junctions

Cell adhesion to the extracellular matrix (ECM) glycoprotein fibronectin can involve: A. the binding of select immunoglobin superfamily members (IgSF) to the Arg-Gly-Asp (RGD) sequence in fibronectin B. the binding of cadherin to the Arg-Gly-Asp (RGD) sequence in fibronectin C. Ca+2 dependent binding of selectins to specific carbohydrate groups on the fibronectin glycoprotein D. the binding of integrins to the Arg-Gly-Asp (RGD) sequence in fibronectin

D. the binding of integrins to the Arg-Gly-Asp (RGD) sequence in fibronectin

Peptides containing the sequence RGD (arginine-glycine-aspartic acid) would be expected to interfere with all of the following functions EXCEPT: A. platelet aggregation B. adhesion of cells to extracellular matrix C. fibroblast movement D. tissue-specific cell sorting

D. tissue-specific cell sorting

True or false? Besides the plasma membranes of the cells, adherens junctions are primarily responsible for the function the columnar epithelium as a permeability barrier.

False

True or false? Cadherins are cell-surface carbohydrate-binding proteins that mediate transient, Ca2+ - dependent cell-cell adhesion in the bloodstream, for example between white blood cells and endothelial cells.

False

True or false? The immunoglobulin superfamily of proteins are calcium-dependent cell adhesion molecules found at desmosomes.

False