Lecture 1,4,5
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Questions and Answers

What is the primary function of collagen in the extracellular matrix?

  • Facilitating cell communication
  • Providing tensile strength (correct)
  • Serving as a bonding agent for cells
  • Enabling stretching and recoil

    • Which specialized cell junction is primarily responsible for anchoring adjacent, non-touching cells?

  • Tight junctions
  • Adherens junctions
  • Desmosomes (correct)
  • Gap junctions

    • Where are tight junctions predominantly located in the body?

  • Between muscle cells
  • Surrounding neurons
  • Within connective tissue
  • In epithelial tissue sheets (correct)

    • Which protein serves the function of promoting cell adhesion in the extracellular matrix?

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

    What physical condition can result from compromised tight junctions in the digestive tract?

    <p>Crohn's disease</p> Signup and view all the answers

    Which type of junction provides a pathway for communication between adjacent cells?

    <p>Gap junctions</p> Signup and view all the answers

    What is the role of elastin in the extracellular matrix?

    <p>Allowing for stretching and recoil</p> Signup and view all the answers

    Which of the following statements about fibronectin is true?

    <p>Lower levels are linked to tumor metastasis.</p> Signup and view all the answers

    What characteristic distinguishes desmosomes from other types of cell junctions?

    <p>They have the strongest cell-to-cell connection.</p> Signup and view all the answers

    What is a key anatomical location where desmosomes can be found?

    <p>Heart and Skin</p> Signup and view all the answers

    What role do Cell Adhesion Molecules (CAMs) play in tissue structure?

    <p>They allow cells to adhere to each other, providing tissue cohesion.</p> Signup and view all the answers

    Which of the following statements about the Extracellular Matrix (ECM) is correct?

    <p>The ECM helps in cell signaling and provides structural support.</p> Signup and view all the answers

    What is a key feature of tight junctions in maintaining intestinal health?

    <p>They create a barrier that prevents the passage of harmful substances.</p> Signup and view all the answers

    Desmosomes are critical for which function within tissues?

    <p>They provide structural integrity by anchoring cells to each other.</p> Signup and view all the answers

    Which type of cell junction allows for the selective exchange of small molecules and ions between adjacent cells?

    <p>Gap junctions</p> Signup and view all the answers

    What is the primary purpose of the Extracellular Matrix (ECM) in tissues?

    <p>To facilitate cell anchoring and provide structural support.</p> Signup and view all the answers

    What characteristic distinguishes CAMs from other membrane proteins?

    <p>They allow for adhesion between adjacent cells.</p> Signup and view all the answers

    Which junctional structure is primarily involved in linking the cytoskeleton of adjacent cells?

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

    What is the significance of the fluid mosaic model in understanding the plasma membrane?

    <p>It highlights the dynamic nature of membrane components and their interactions.</p> Signup and view all the answers

    Which statement accurately describes the extracellular matrix (ECM)?

    <p>The ECM is composed of a combination of proteins and carbohydrates and provides structural and biochemical support to surrounding cells.</p> Signup and view all the answers

    What role do cell adhesion molecules (CAMs) play in cellular structures?

    <p>CAMs are proteins that help cells stick to each other and to their surroundings, promoting tissue integrity.</p> Signup and view all the answers

    Which description best defines desmosomes and their function?

    <p>Desmosomes are adhesive structures that anchor cells together, providing mechanical strength to tissues.</p> Signup and view all the answers

    How do tight junctions contribute to intestinal health?

    <p>Tight junctions provide a selective barrier that regulates what substances can pass through the intestinal lining.</p> Signup and view all the answers

    Which type of cell junction provides the most significant barrier to paracellular transport?

    <p>Tight junctions</p> Signup and view all the answers

    Which is NOT a key characteristic of the extracellular matrix (ECM)?

    <p>It includes peroxisomes that detoxify harmful substances.</p> Signup and view all the answers

    Which type of junction is primarily involved in the communication between adjacent cells?

    <p>Gap junctions</p> Signup and view all the answers

    What is the primary structural component of desmosomes?

    <p>Intermediate filaments anchoring to desmogleins and desmocollins</p> Signup and view all the answers

    Which statement accurately describes the function of adherens junctions?

    <p>They anchor adjacent cells together and link them to the actin cytoskeleton.</p> Signup and view all the answers

    What is a primary function of gap junctions in the context of cell junctions?

    <p>They serve as channels that allow passive transport of ions and small molecules between cells.</p> Signup and view all the answers

    What is a primary function of the extracellular matrix (ECM) in tissue organization?

    <p>Facilitating cell adhesion and communication</p> Signup and view all the answers

    Which of the following best describes cell adhesion molecules (CAMs)?

    <p>Proteins that help cells recognize and attach to each other</p> Signup and view all the answers

    What is the primary role of desmosomes in cellular structures?

    <p>Promoting mechanical strength by linking adjacent cells</p> Signup and view all the answers

    How do tight junctions contribute to intestinal health?

    <p>They create a barrier to prevent pathogen invasion.</p> Signup and view all the answers

    Which type of cellular junction is characterized by linked cytoskeletons of adjacent cells?

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

    What is the primary function of the plasma membrane in relation to cell communication?

    <p>To control the movement of signaling molecules and ions</p> Signup and view all the answers

    Which statement correctly distinguishes between gap junctions and tight junctions?

    <p>Gap junctions facilitate rapid communication between cells; tight junctions prevent leakage.</p> Signup and view all the answers

    What role do intermediate filaments play in maintaining cellular integrity?

    <p>They provide rigidity and prevent mechanical stress damage.</p> Signup and view all the answers

    Which feature is not a function of the cytoskeleton?

    <p>Production of energy in the mitochondria</p> Signup and view all the answers

    Which cellular structure is involved in both muscle contraction and amoeboid movement?

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

    Study Notes

    Cell Structure and Function

    • Cell Theory Principles: Basic unit of life; all organisms are composed of cells; cells function based on structure.
    • Common Features of Cells: Plasma membrane, cytosol, and nucleus.
    • Diversity of Cells: Trillions of cells classified into approximately 200 types based on specific structures and functions.

    Plasma Membrane

    • Also known as the cell membrane; acts as a barrier between the cell and its environment.
    • Functions: Controls the movement of ions, waste, and nutrients; plays a role in cell-to-cell communication.
    • Composed of a thin phospholipid bilayer with proteins and some carbohydrates.

    Extracellular Matrix (ECM)

    • Abundant in connective tissue; absent in epithelial tissue.
    • Contains proteins such as collagen, elastin, and fibronectin, made mostly by fibroblasts.

    Proteins in ECM

    • Collagen: Cable-like fibers providing tensile strength; most abundant protein, constituting half of body protein by weight.
    • Elastin: Rubber-like fibers allowing stretching and recoil.
    • Fibronectin: Functions as biological glue; promotes cell adhesion; decreased levels associated with tumor metastasis.

    Specialized Cell Junctions

    • Desmosomes: Strongest cell-to-cell connections, providing additional strength; prevalent in heart, skin, and uterus.
    • Tight Junctions: Seal adjacent cells together to prevent passage between them; found in epithelial tissues like the digestive tract.
    • Gap Junctions: Communicate between adjacent cells through small tunnel-like connections, enabling signaling molecules to pass.

    Fluid Mosaic Model

    • Describes plasma membrane structure as dynamic and non-uniform.
    • Composed of a phospholipid bilayer with integral and peripheral proteins; lipids greatly outnumber proteins.

    Cellular Proteins

    • Channel Proteins: Facilitate passive transport of molecules.
    • Carrier Proteins: Transport specific molecules like glucose.
    • Enzymatic Proteins: Catalyze biochemical reactions at the membrane.
    • Receptor Proteins: Receive signals from external molecules.
    • Cell Adhesion Molecules (CAMs): Help cells adhere to each other.

    Cytoskeleton

    • Comprised of three main elements:
      • Microtubules: Hollow tubes providing structure and facilitating transport; essential for cilia and flagella movement.
      • Microfilaments: Composed of actin; involved in muscle contraction and amoeboid movement.
      • Intermediate Filaments: Threadlike proteins providing mechanical support.

    Cytosol

    • Often referred to as "cell gel"; site of intermediary metabolism.
    • Contains enzymes for metabolic reactions, transport vesicles for moving products, and inclusions for nutrient storage.

    Organelles and Their Functions

    • Nucleus: Houses DNA; directs protein synthesis.
    • Endoplasmic Reticulum (ER): Site of protein and lipid production; Rough ER synthesizes proteins, while Smooth ER packages secretory products.
    • Golgi Complex: Modifies, packages, and distributes proteins.
    • Lysosomes: Contain hydrolytic enzymes for breaking down organic molecules.
    • Peroxisomes: Detoxify harmful substances using oxidative enzymes.
    • Centrioles: Essential for organizing microtubules during cell division.

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