Cell Junctions and Extracellular Matrix Quiz

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Questions and Answers

What describes the basal surface of an epithelial cell?

It faces the lumen of a cavity.

It is characterized by numerous tight junctions.

It is the exposed free surface of the cell.

It rests on the basal lamina separating the epithelium from other tissue. (correct)

What is the primary function of cadherin in epithelial tissues?

To mediate homophilic cell-cell adhesion in animal tissues. (correct)

To connect cells to actin filaments.

To support the signaling pathways within cells.

To anchor cells to the extracellular matrix.

Which of the following best describes anchoring junctions?

They are responsible for tight sealing between epithelial cells.

They typically consist of transmembrane adhesion proteins connecting to the cytoskeleton. (correct)

They form channels for cell communication.

They are specialized for cell migration.

What is the role of integrin in epithelial tissues?

To facilitate attachment of cells to the extracellular matrix and to each other. Signup and view all the answers

What characteristic distinguishes desmosomes from other cell junctions?

They contain dense plaques of protein. Signup and view all the answers

What is the main function of cell junctions in multicellular organisms?

To hold cells together and govern tissue architecture Signup and view all the answers

Which component of connective tissue bears most of the mechanical stress?

The extracellular matrix Signup and view all the answers

What role does the extracellular matrix play in cellular behavior?

It governs the making and breaking of cellular attachments. Signup and view all the answers

How do defects in cell junctions and the extracellular matrix affect health?

They are linked to various diseases. Signup and view all the answers

In epithelial tissue, what is the primary stress-bearing component?

The cytoskeleton of the cells Signup and view all the answers

What mediates the attachment of connective tissue cells to the extracellular matrix?

Cell adhesion proteins Signup and view all the answers

Why is the extracellular matrix crucial for the organization of multicellular structures?

It helps cells sense and respond to environmental changes. Signup and view all the answers

What initiates changes in cell orientation and behavior within tissues?

Cell attachments to the extracellular matrix and other cells Signup and view all the answers

What type of junction is primarily responsible for sealing gaps between epithelial cells to prevent molecule leakage?

Tight junctions Signup and view all the answers

Which type of adhesion protein is mainly involved in cell-to-cell junctions?

Cadherins Signup and view all the answers

What is the primary function of desmosomes in epithelial tissue?

Linking intermediate filaments of neighboring cells Signup and view all the answers

Which junction type links actin filaments to the extracellular matrix?

Actin-linked cell–matrix junctions Signup and view all the answers

Which of the following junctions is found at the basal surface of epithelial cells?

Hemidesmosomes Signup and view all the answers

How do gap junctions contribute to epithelial function?

They connect the cytoplasms of adjacent cells. Signup and view all the answers

Which of the following is a feature of the basal lamina?

It underlies epithelial tissue. Signup and view all the answers

What distinguishes adherens junctions from desmosomes?

Adherens junctions provide less mechanical strength than desmosomes. Signup and view all the answers

Which of the following best describes the structure of a junctional complex in epithelial cells?

It is made up of tight junctions, adherens junctions, and desmosomes. Signup and view all the answers

What role do transmembrane adhesion proteins play in junctions?

They span the plasma membrane and link to extracellular structures. Signup and view all the answers

Which of the following statements is true about integrins?

They typically link cells to the extracellular matrix. Signup and view all the answers

What is one function of the extracellular matrix in connective tissue?

To provide structural support and facilitate communication. Signup and view all the answers

Why might certain integrins mediate cell–cell adhesion instead of cell–matrix attachment?

There are exceptions to the usual functions of integrins. Signup and view all the answers

What kind of tissue resides beneath epithelial tissue?

Connective tissue Signup and view all the answers

Study Notes

Cell Junctions and the Extracellular Matrix

Cells in multicellular organisms are held together by direct interactions or within the extracellular matrix (ECM).
ECM is a complex network of proteins and polysaccharides secreted by cells.
Cell cohesion is crucial for organized multicellular structures that can withstand external forces.
Cell attachments govern tissue architecture, and cell movement during growth, development, and repair.
Attachments control cytoskeleton orientation and responses to environmental changes.
ECM defects link to various diseases.

Connective Tissues

Connective tissues (e.g., bone, tendon) have an ECM that bears most of the stress.
Cells are sparsely distributed within the ECM.
Cell–matrix junctions link connective tissue cells to the ECM.
Allow cells to move and sense mechanical changes in the matrix.

Epithelial Tissues

Epithelial tissues (e.g., gut lining, skin) have cells tightly bound into sheets (epithelia).
ECM is less pronounced, mainly as a basal lamina/basement membrane.
Cell–cell junctions (anchoring junctions) anchor cells directly.
Cytoskeletons are linked, transmitting stresses across the cells.
Cell–matrix junctions link epithelial cells to the basal lamina.

Cell Junctions: Types and Structure

Cell–cell junctions link cell cytoskeletons:
- Adherens junctions connect to actin filaments.
- Desmosomes link to intermediate filaments.
- Tight junctions seal gaps between cells to prevent leakage.
- Gap junctions form channels, linking cells' cytoplasm.
Cell–matrix junctions link cell cytoskeletons to the ECM:
- Actin-linked cell–matrix junctions anchor actin filaments.
- Hemidesmosomes anchor intermediate filaments.

Adhesion Proteins

Transmembrane adhesion proteins link cytoskeleton to ECM or other cells.
Cadherin superfamily primarily mediates cell–cell adhesion.
Integrin superfamily primarily mediates cell–matrix adhesion.
Specialization within each family (cadherins/actin, cadherins/intermediate filaments, integrins/actin, integrins/intermediate filaments).

Junctions Table Summary

Junction types are summarized in Table 19-1 matching transmembrane adhesion proteins, extracellular ligands, and their intracellular cytoskeletal attachments.
Some integrins also mediate cell–cell adhesion.
Other cell adhesion molecules exist for transient cell–cell attachments.

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Description

Test your knowledge on cell junctions and the extracellular matrix (ECM) in multicellular organisms. This quiz covers the structure, function, and significance of the ECM in maintaining tissue architecture and its role in health and disease. Explore the connections between cells and connective tissues as well as epithelial tissues.