Chapter 4 Extracellular matrix, Cell junction and cell adhension

Content of this chapter

Outline

1. The extracellular space: Extracellular Matrix

         A.The extracellular matrix (ECM)

         B. Components of the ECM

          (1) Collagen                                                                   
          (2). Proteoglycans(PGs)

          (3). Noncollagen components of the ECM

2. Cell-Cell adhesion and communication

         A. Major types of cell junctions in animal cells
         B. Tight junctions: Sealing the extracellular space 

         C. Gap junctions allow direct electrical and chemical communication between cells .--TO integrate the activity of adjacent cells        
         D. Desmosomes: Joining adjacent cells together

         E. Adherens junction(belt desmosome)

3. Cell-Matrix adhesion

         A. Integrins

         B. Focal contacts and hemidesmosomes

4. Cell adhesion molecule Families

         A. Selectins recognize and bind to specific arrangement of oligosaccharide
         groups on surfaces of cell.
        B. Immunoglobulins: most IgSF cell-adhesion molecules mediate the specific  interactions of lymphocytes with cells required for an immune response. Some of IgSF cell-adhesion molecules (VCAM and NCAM) mediate adhesion  between nonimmune cells.
        C. Cadherins: family of glycoproteins, that mediate Ca2+ dependent cell  adhesion and transmit signals from the ECM to the cytoplasm.

5. Plasmodesmata directly connect the cytosol of adjacent cells in higher plants

6. Cell walls

         A. Plant cell walls provide protection against abrasion, osmotic stress,  and pathogens.

         B. Microfibrils of cellulose form the fibrous component of the cell wall.
        C. The matrix of cell wall contains hemicellulose, pectins, and hydroxyproline-rich,proline-rich, and glycine-rich structural proteins.
         D. Primary cell walls are flexible to allow growth after division.
        E. Mature secondary cell walls are thicker and more rigid.