4.6 Connections between Cells and Cellular Activities - Biology 2e
Learning Objectives
- Describe the extracellular matrix.
- List examples of plant and animal cell communication.
- Summarize roles of tight junctions, desmosomes, gap junctions, and plasmodesmata.
Extracellular Matrix of Animal Cells
- Components: Proteins, primarily collagen, interwoven with proteoglycans.
- Function: Holds cells together in tissue, facilitates cell communication.
- Communication Mechanism:
- Receptors on plasma membranes bind to molecules, altering the receptor's structure.
- Changes in receptor structure affect microfilaments inside the cell.
- This induces chemical signals that can alter protein production and cell activities.
- Example: Blood clotting involves extracellular matrix communication to initiate clotting factors.
Intercellular Junctions
- Cells communicate through direct contact.
- Types:
Plasmodesmata (Plant Cells)
- Channels between plant cell walls allowing transport of materials.
- Connects cytoplasm of adjacent cells.
- Facilitates transport from roots to leaves via vascular tissues (xylem and phloem).
Tight Junctions (Animal Cells)
- Watertight seals between adjacent cells, held by proteins (claudins and occludins).
- Prevents material leakage between cells.
- Common in epithelial tissues, e.g., bladder lining.
Desmosomes (Animal Cells)
- "Spot welds" between cells, connecting via cadherins to intermediate filaments.
- Maintains cells in tissues that stretch (e.g., skin, heart).
Gap Junctions (Animal Cells)
- Channels forming between adjacent cells for ions, nutrients transport.
- Formed by connexons (six protein structure).
- Critical in cardiac muscle for synchronized contraction.
Link to Learning
Citation
- Authors: Mary Ann Clark, Matthew Douglas, Jung Choi
- Publisher: OpenStax
- Book Title: Biology 2e
- Section URL: OpenStax Biology 2e
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