Cell Adhesion and Signalling Quiz
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Questions and Answers

Which of the following is a property of the extracellular matrix (ECM)?

  • Prevents cell division
  • Provides structural support (correct)
  • Contains no molecular components
  • Acts as a barrier to cell communication

    • Epithelial tissues have a rich extracellular matrix and few cell-cell adhesions.

    False

    What is the primary role of adhesion molecules in the body?

    To allow cells to adhere to each other and to the extracellular matrix.

    Cells and other components are organized into ________.

    <p>tissues</p> Signup and view all the answers

    Match the following types of tissue with their characteristics:

    <p>Epithelial tissues = Sheets of tightly bound cells Connective tissues = Rich in ECM components with few cells Extracellular matrix = Network of macromolecules Adhesion molecules = Facilitate cell-cell and cell-matrix adhesion</p> Signup and view all the answers

    Which of the following is NOT a function of the extracellular matrix?

    <p>Preventing immune cell interaction</p> Signup and view all the answers

    Name one type of cell that is commonly found in connective tissues.

    <p>Fibroblasts</p> Signup and view all the answers

    Which type of collagen binds type II fibrils in cartilage?

    <p>Type IX</p> Signup and view all the answers

    Elastic fibers provide tensile strength to tissues.

    <p>False</p> Signup and view all the answers

    What is the main component of elastic fibers?

    <p>Elastin</p> Signup and view all the answers

    Fibronectin helps attach cells to the _____.

    <p>ECM</p> Signup and view all the answers

    Match the types of collagen with their locations:

    <p>Type I = Tendons Type II = Cartilage Type IX = Cartilage Type XII = Tendons</p> Signup and view all the answers

    What is the main function of connective tissue?

    <p>Providing routes for communication and supply</p> Signup and view all the answers

    The extracellular matrix (ECM) does not determine the physical properties of connective tissues.

    <p>False</p> Signup and view all the answers

    Name one component of the extracellular matrix (ECM).

    <p>glycosaminoglycan or fibrous protein</p> Signup and view all the answers

    Tendons have a ______ tensile strength due to collagen fibrils.

    <p>high</p> Signup and view all the answers

    Match the type of connective tissue with its characteristic:

    <p>Tendon = Rope-like, high tensile strength Blood vessels = Resilient, flexible Cartilage = Tensile strength and elastic properties Bone = Rigid and incompressible</p> Signup and view all the answers

    Which of the following is a type of glycosaminoglycan?

    <p>Hyaluronan</p> Signup and view all the answers

    Fibroblasts are primarily responsible for the production of extracellular matrix components.

    <p>True</p> Signup and view all the answers

    What provides the tensile strength and elastic properties in cartilage?

    <p>collagen and proteoglycan aggrecan</p> Signup and view all the answers

    The vitreous content of the eye has a ______ jelly-like consistency.

    <p>transparent</p> Signup and view all the answers

    Which type of tissue is characterized by a rigid and incompressible structure?

    <p>Bone</p> Signup and view all the answers

    Which of the following is NOT a type of glycosaminoglycan (GAG)?

    <p>Collagen</p> Signup and view all the answers

    Hyaluronan is a type of GAG that is sulphated.

    <p>False</p> Signup and view all the answers

    What are the two sugars that make up the repeating disaccharide units of GAGs?

    <p>an amino sugar and a uronic acid</p> Signup and view all the answers

    The highly negatively charged groups in GAGs include _____ and _____ groups.

    <p>sulphate, carboxyl</p> Signup and view all the answers

    Match the following components with their descriptions:

    <p>Fibronectin = A glycoprotein that helps cells attach to the extracellular matrix Osteopontin = A protein that regulates bone mineralization Vitronectin = A glycoprotein involved in cell adhesion and migration Tenascin = An extracellular matrix protein involved in tissue repair</p> Signup and view all the answers

    What is the maximum length of a hyaluronan chain?

    <p>25,000 disaccharide units</p> Signup and view all the answers

    All GAGs are made up of sulphated sugars.

    <p>False</p> Signup and view all the answers

    Name one of the four main groups of glycosaminoglycans.

    <p>Hyaluronan</p> Signup and view all the answers

    GAGs are composed of _____ polysaccharide chains.

    <p>unbranched</p> Signup and view all the answers

    Which of the following statements about GAGs is true?

    <p>One of the sugars in GAGs is always an amino sugar.</p> Signup and view all the answers

    What percentage of carbohydrate can proteoglycans contain by weight?

    <p>95%</p> Signup and view all the answers

    Collagens are primarily composed of lipids.

    <p>False</p> Signup and view all the answers

    Name one type of carbohydrate molecule that is found in proteoglycans.

    <p>Glycosaminoglycans (GAGs)</p> Signup and view all the answers

    Collagen trimers self-assemble into ______.

    <p>fibrils</p> Signup and view all the answers

    Match the following types of collagen with their characteristics:

    <p>Fibrillar collagens = Form fibrils and bundles, major ECM components Fibril-associated collagens = Do not form fibrils, bind to fibrils Type I collagen = Most abundant collagen type in skin and bone Type II collagen = Found predominantly in cartilage</p> Signup and view all the answers

    What is the typical sequence of amino acids that forms a collagen helix?

    <p>Gly-X-Y</p> Signup and view all the answers

    The human genome contains 42 genes for collagen alpha-chains.

    <p>True</p> Signup and view all the answers

    What does the term 'scurvy' refer to in the context of collagen synthesis?

    <p>Vitamin C deficiency</p> Signup and view all the answers

    The major fibrous extracellular matrix component, collagen, represents ______% of total protein mass in mammals.

    <p>25</p> Signup and view all the answers

    Which amino acid is commonly found in the gly-X-Y sequence of collagen?

    <p>Proline</p> Signup and view all the answers

    Study Notes

    Cell Adhesion and Cell Signalling

    • Topics include adhesion in epithelia, the extracellular matrix, and cell-cell/cell-matrix adhesion
    • Learning objectives include describing ECM components, understanding how ECM contributes to tissue structure and function, discussing adhesion molecules, and understanding cellular signalling

    Learning Objectives Details

    • Describe molecular components of the extracellular matrix (ECM) and their structures, properties, and functions
    • Understand how the ECM contributes to tissue structure and function
    • Discuss various families of adhesion molecules that allow cells to adhere to the ECM and each other
    • Understand the importance of adhesion molecules in cellular functions, particularly in the immune system
    • Understand the role of adhesion in tissues, especially epithelial tissues
    • Understand principles of cellular signalling and examples of signalling pathways and components

    ECM and Cell Adhesion

    • Cells adhere to each other and the extracellular matrix (ECM) to form multicellular organisms
    • Tissues are composed of cells and ECM, which is a network of macromolecules
    • Cell adhesion mechanisms and ECM are critical for tissue organization, development, function, and dynamics
    • The relative importance of cell-cell and cell-matrix adhesions varies between tissue types

    Tissue Organisation Extremes

    • Epithelial tissues have tightly bound cells, linked to the cytoskeleton, and a thin ECM layer
    • Connective tissues have a rich ECM (e.g., collagen fibers), fewer cells (e.g., fibroblasts, immune cells), and fewer cell-cell adhesions; cell-matrix adhesions are more important.

    ECM Macromolecules

    • Two main ECM components:
      • Glycosaminoglycans (GAGs): Polysaccharide chains (e.g., heparin sulfate, hyaluronan) often linked to proteins (proteoglycans)
      • Fibrous proteins: (e.g., collagen, fibrillin, elastin, laminin)
    • Adhesive glycoproteins act as adapters (e.g., fibronectin, fibrinogen) binding matrix proteins, cells, or both to provide molecular interactions

    GAGs

    • Unbranched polysaccharide chains with repeating disaccharide units
    • One is an amino sugar (N-acetylglucosamine or N-acetylgalactosamine); the other is often a uronic acid
    • Highly negatively charged (sulfate and carboxyl groups)
    • Four major groups: hyaluronan, chondroitin sulfate, dermatan sulfate, heparan sulfate, keratan sulfate

    Hyaluronan

    • Extremely long chain, non-sulphated
    • Attracts water, creating a non-compressible filler

    Proteoglycans

    • Proteoglycans are a type of GAG, consisting of a core protein with covalently attached GAG chains
    • Often involved in cell surface interactions, and structural support.

    Collagen

    • Major fibrous component of the ECM (25% of total animal protein)
    • 42 human genes for collagen a-chains that form triple helixes
    • Different combinations create diverse collagen types (~30) expressed in varying tissues

    Elastic Fibres

    • Provide resilience and recoil ability in some tissues (e.g., blood vessels, lungs, skin)
    • Elastin is the main component (hydrophobic protein)
    • Elastin is secreted as tropoelastin and is then cross-linked into networks within elastic fibres
    • Elastic fibres also contain microfibrils (eg. fibrillin)

    Fibronectin

    • Forms dimers that have multiple domains
    • Multiple binding sites for other components (collagen, integrins) and cells

    Basal Lamina (Basement Membrane)

    • Thin, tough, flexible ECM sheet
    • Essential for mechanical roles (e.g., connecting epidermis to dermis), and is present underneath epithelia and surrounding muscle/nerve cells
    • Composed of type IV collagen, perlecan, laminin, and nidogen

    ECM remodelling

    • Processes like tissue development, wound healing, and bone remodelling involve ECM degradation mediated by proteases (e.g., matrix metalloproteases (MMPs))

    Roles of the Extracellular Matrix

    • Provides structural support, scaffolding for cells
    • Reservoir for growth factors and cytokines
    • Provides pathways for cell migration
    • Regulates cell shape, polarity, survival, proliferation, and differentiation
    • Regulates tissue development

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    Cell Adhesion and Cell Signalling PDF

    Description

    Test your knowledge on cell adhesion and cell signalling, focusing on the extracellular matrix and various adhesion molecules. This quiz covers the roles of cellular adhesion in tissue structure, function, and related signaling pathways, particularly in epithelial tissues and the immune system.

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