Cell Junctions and Extracellular Matrix

Which of the following is a major function of anchoring junctions?

A. Creating tight seals to prevent molecule leakage
B. Connecting cytoskeletal elements to adjacent cells or matrix
C. Forming open channels between cells
D. Facilitating rapid electrical signaling

B. Connecting cytoskeletal elements to adjacent cells or matrix

What type of cytoskeletal element is linked by desmosomes?

A. Microtubules
B. Actin filaments
C. Intermediate filaments
D. Laminin networks

C. Intermediate filaments

Cadherins require which ion to mediate cell-cell adhesion?

A. Mg²⁺
B. Na⁺
C. K⁺
D. Ca²⁺

D. Ca²⁺

Which type of junction is primarily responsible for preventing leakage between epithelial cells?

A. Desmosome
B. Gap junction
C. Tight junction
D. Hemidesmosome

C. Tight junction

What differentiates hemidesmosomes from desmosomes?

A. Hemidesmosomes link to actin, desmosomes to intermediate filaments
B. Hemidesmosomes connect cells to matrix; desmosomes connect cells to each other
C. Both link to extracellular matrix
D. Both use cadherins as adhesion proteins

B. Hemidesmosomes connect cells to matrix; desmosomes connect cells to each other

What component initiates the structure of the basal lamina?

A. Type I collagen
B. Laminin
C. Integrin
D. Fibronectin

B. Laminin

Which proteins connect cadherins to actin filaments in adherens junctions?

A. Talin and vinculin
B. Nidogen and perlecan
C. α-catenin, β-catenin, and p120-catenin
D. Fibronectin and collagen

C. α-catenin, β-catenin, and p120-catenin

Gap junctions primarily serve to:

A. Anchor intermediate filaments to the plasma membrane
B. Seal neighboring cells to prevent fluid leakage
C. Allow passage of small molecules and ions between adjacent cells
D. Facilitate adhesion to the basal lamina

C. Allow passage of small molecules and ions between adjacent cells

What triggers integrins to transition from inactive to active state?

A. Increased glucose uptake
B. Extracellular Ca²⁺ binding
C. Mechanical tension or intracellular signaling
D. Phosphorylation of β-catenin

C. Mechanical tension or intracellular signaling

In embryonic development, cadherins mediate cell sorting based on:

A. Membrane voltage
B. Matrix rigidity
C. Cadherin type and expression level
D. Gap junction abundance

C. Cadherin type and expression level

What would most likely happen to epithelial cell adhesion if extracellular Ca²⁺ were removed?

A. Integrin-mediated adhesions would increase
B. Cadherin-mediated adhesions would fail
C. Collagen fibrils would denature
D. Actin polymerization would be inhibited

B. Cadherin-mediated adhesions would fail

Which of the following cell junction types is involved in mechanotransduction?

A. Gap junctions
B. Tight junctions
C. Adherens junctions
D. Hemidesmosomes

C. Adherens junctions

In which location are tight junctions typically found in epithelial cells?

A. Near the basal surface
B. Randomly distributed
C. Near the apical surface
D. Deep within the cytoplasm

C. Near the apical surface

Which adaptor protein is involved in linking integrins to actin filaments in cell-matrix junctions?

A. α-catenin
B. Vinculin
C. Talin
D. β-catenin

C. Talin

Which ECM component is primarily responsible for forming the sheet-like structure of the basal lamina?

A. Type I collagen
B. Fibronectin
C. Laminin
D. Integrin

C. Laminin

The selective adhesion between cells during embryonic development is primarily driven by:

A. Gap junction communication
B. Homophilic binding of cadherins
C. Competition for integrin ligands
D. Expression of collagen isoforms

B. Homophilic binding of cadherins

Which cell junction type allows electrical and metabolic coupling between adjacent cells?

A. Desmosomes
B. Tight junctions
C. Gap junctions
D. Hemidesmosomes

C. Gap junctions

aminins are composed of which three subunits?

A. α, β, and δ
B. α, β, and γ
C. β, γ, and ε
D. α, β, and ζ

B. α, β, and γ

Which of the following is a key function of the basal lamina?

A. Generating contractile force
B. Serving as a diffusion channel
C. Organizing proteins in adjacent plasma membranes
D. Transcribing ECM genes

C. Organizing proteins in adjacent plasma membranes

In hemidesmosomes, which transmembrane protein links intermediate filaments to the extracellular matrix?

A. Cadherin
B. Vinculin
C. Integrin
D. Laminin

C. Integrin