Download - AP Bio Ch. 7 part 2 The extracellular matrix
The extracellular
matrixECM
The area between
cells
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
Components of the ECM
• Cells secrete glycoproteins – This is the main
component of the ECM
All 3 of these are common ECM glycoproteins
• Collagen is the most common glycoprotein in the ECM
• Proteoglycans (a glycoprotein) form a woven network outside cells
• Collagen are like strong fibers that run throughout this network
• 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
Quick Think
Explain the role of:
•Fibronectins
•Collagen fibers
•Proteoglycans
in the extracellular matrix
The ECM allows for cell to cell communication
Intercellular junctions
• Cells in plants and animals are organized into tissues, organs, and organ systems
• Cells in a tissue may adhere to each other
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
• Water, solutes, even proteins and RNA can move between cells
• Allows plant cells to function as a unified system, rather than isolated cells
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)
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
Desmosomes or anchoring junctions in animal cells
• Like rivets that fasten cells together in strong sheets
• Keratin filaments anchor these attachments in the cytoplasm
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
Quick Think:
Summarize the role and location of each of the 3 types of intercellular junctions