1 The extracellular matrix ECM The area between

� 1. The extracellular matrix ECM The area between cells � 2. The ECM of animal cells • Animals cells lack the structure and support that a cell wall provides • Have an ECM instead that provides some of the same support � 3. Components of the ECM • Cells secrete glycoproteins – This is the main component of the ECM All 3 of these are common ECM glycoproteins � 4. • Collagen is the most common glycoprotein in the ECM � 5. • Proteoglycans (a glycoprotein) form a woven network outside cells • Collagen are like strong fibers that run throughout this network � 6. • Cells are attached to the ECM by another glycoprotein: fibronectin • On one side, fibronectin is attached to proteins in the plasma membrane • On the other side, the fibronectin is attached to the glycoproteins of the ECM � 7. the role of: • Fibronectins • Collagen fibers • Proteoglycans in the extracellular matrix

� � � � The ECM allows for cell to cell communication 9. Intercellular junctions • Cells in plants and animals are organized into tissues, organs, and organ systems • Cells in a tissue may adhere to each other 10. The Plasmodesmata of plants • Cells walls of plants are perforated with small channels called plasmodesmata • Cytosol passes through the channel, thereby connecting the two cells 11. • Water, solutes, even proteins and RNA can move between cells • Allows plant cells to function as a unified system, rather than isolated cells 12. Intercellular Junctions in Animal Cells • 3 main types of junctions between animal cells • These junctions are most common in epithelial tissue (skin, linings of organs, etc) 13. Tight junctions in animal cells • The plasma membranes of neighboring cells are very tightly pressed together and bound by proteins • Forms a seal or barrier around a group of cells 14. Desmosomes or anchoring junctions in animal cells • Like rivets that fasten cells together in strong sheets • Keratin filaments anchor these attachments in the cytoplasm 15. Gap junctions (or communicating junctions) in animal cells • Similar to plasmodesmata in plant cells • Provides a channel between cells that cytosol can travel through • Allows for cell to cell communication – Important in cardiac tissue and embryonic tissue