YH

Biol 123 Lecture: Cytoskeleton and Tissues

  • Lecture Information:
    • Caroline offers office hours every Tuesday from 9:30 to 10:30 am at room 470-113.
    • Students can also reach out via email caroline.josefsson@viu.ca or drop by without an appointment.
    • Access VIULearn for reading guides and lecture slides.
  • Social Media for VIU Restoration Project:
    • Check out the IG handle @viu_restoration and the iNaturalist project, ‘VIU Garry Oak Ecosystem’.
    • To join the restoration project, contact Caroline via email.
  • Chapter 10: Cell and Tissue Form
    • Discusses how molecular and cellular structures inform tissue function and overall organismal organization.
  • 10.1 Tissues and Organs:
    • Definition of Tissue:
    • A group of cells performing a specific function.
    • Types of Animal Tissues:
    • Epithelial Tissue
    • Connective Tissue
    • Muscle Tissue
    • Nervous Tissue
    • Organ Formation:
    • Composed of multiple tissues working synergistically.
    • Example: Skin:
      • Epidermis: Epithelial tissue (outer layer).
      • Dermis: Connective tissue (inner layer).
  • 10.1.1 Epithelial Tissue:
    • Composed of tightly joined cell layers.
    • Covers body surfaces, gut linings, and blood vessels.
    • Attached to the basal lamina (a type of extracellular matrix, ECM) composed of proteoglycans and fibrous proteins.
  • 10.1.2 Connective Tissue:
    • Characterized by fewer cells and a significant amount of ECM.
    • Provides structural support and flexibility.
    • Key cell type in dermis: Fibroblasts (synthesize ECM).
    • Role: Nutrient transport to the epidermis and aids in wound healing.
  • 10.2 The Cytoskeleton:
    • Internal support structure for cells; components include:
    • Microfilaments:
      • Composed of actin monomers forming double helices.
      • Thin, branched structure, crucial for cell shape, adhesion, and movement.
    • Intermediate Filaments:
      • Strong fibers made from various protein subunits.
      • Provide mechanical strength, lacking motor proteins.
      • Important for cell adhesion and structural integrity (e.g., keratins, vimentins).
    • Microtubules:
      • Comprised of tubulin dimers (α-tubulin and β-tubulin).
      • Thickest, providing structure and compressive strength, supporting intracellular transport and cell movement.
  • Functions of Cytoskeletal Elements:
    • Microfilaments:
    • Roles: Cell shape, movement, division (cytokinesis), and vesicle transport.
    • Intermediate Filaments:
    • Roles: Provide shape and support.
    • Microtubules:
    • Roles: Cell shape, cilia and flagella movement, chromosomal segregation during cell division, and organelle arrangement.
  • Motor Proteins Interacting with Cytoskeletal Elements:
    • Microfilament Motors:
    • Myosin:
      • Moves toward the plus end, involved in muscle contraction, cell crawling, and cytokinesis.
    • Microtubule Motors:
    • Kinesin:
      • Transports organelles and vesicles toward the microtubule plus end.
    • Dynein:
      • Moves cargo toward the minus end, involved in cilia movement.
  • Cilia Movement:
    • Caused by microtubules and dynein, aiding in movement across surfaces (e.g., respiratory tract).
  • Impacts of Cytoskeletal Dysfunction:
    • Example: Epidermolysis bullosa results from mutations affecting adhesion proteins in the epidermis, leading to decreased cell-cell adhesion and structural integrity.
  • Gene Therapy Considerations:
    • Advances are being made in treating genetic skin disorders through topical and ex vivo therapies.
  • Conclusion and Review Strategy:
    • Use Table 10.1 to summarize major cytoskeletal elements and functions.
    • Pause to review motor protein actions relative to cytoskeletal tracks.
    • Discuss differences between microtubules/microfilaments and intermediate filaments.
    • Explore potential cellular mutations and their impacts in further discussions.