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 mainly of cellulose fibers in a matrix of polysaccharides and proteins, forming a rigid outer layer.
- Function: Provides support, regulates water intake, and allows communication via plasmodesmata.
2. The Extracellular Matrix (ECM) of Animal Cells
- Composition: Made of glycoproteins like collagen, proteoglycans, and fibronectin, forming a complex network.
- Function: Provides support, separates tissues, and influences cell behavior such as movement, growth, and development.
3. Intercellular Junctions
- Plasmodesmata (Plants): Channels through cell walls enabling transport and signaling between plant cells.
- Tight Junctions (Animals): Seal neighboring cells together to prevent leakage of extracellular fluid.
- Desmosomes: Anchor cells into strong sheets; important for tissues under mechanical stress.
- Gap Junctions: Permit direct exchange of ions and small molecules for coordinated cellular responses.
In a Nutshell
- Extracellular structures and junctions maintain tissue structure and facilitate communication between cells.
- They enable coordination and cohesion among cells, supporting the organism's overall functionality.