Rucete ✏ Campbell Biology In a Nutshell
Unit 2 THE CELL — Concept 6.7 Extracellular Components and Connections Between Cells Help Coordinate Cellular Activities
Cells are not isolated entities; they interact with their environment and neighboring cells through various structures that provide support, communication, and coordination.
1. Plant Cell Walls
Structure: Composed primarily of cellulose fibers embedded in a matrix of polysaccharides and proteins, forming a rigid layer outside the plasma membrane.
Function: Provides structural support, protection, and regulates water intake. It also mediates communication between cells through plasmodesmata.
2. The Extracellular Matrix (ECM) of Animal Cells
Composition: Consists of glycoproteins like collagen, proteoglycans, and fibronectin, which form a complex network surrounding cells.
Function: Offers structural support, segregates tissues, and facilitates intercellular communication. It influences cell behavior, including migration, proliferation, and differentiation.
3. Intercellular Junctions
Plasmodesmata in Plant Cells: Channels that traverse cell walls, allowing transport of water, nutrients, and signaling molecules between adjacent cells, thus enabling coordination.
Tight Junctions in Animal Cells: Create a watertight seal between cells, preventing leakage of extracellular fluid across epithelial layers.
Desmosomes: Act like rivets, fastening cells together into strong sheets, providing mechanical stability to tissues subjected to stress.
Gap Junctions: Channels that permit direct communication between neighboring cells by allowing the passage of ions and small molecules, facilitating coordinated responses.
In a Nutshell
Extracellular components and cell junctions are crucial for maintaining the structural integrity of tissues and organs.
They enable cells to adhere to each other and communicate effectively, ensuring coordinated functions necessary for the organism's overall well-being.