Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 18 Cell Junctions, Cell Adhesion, and the Extracellular Matrix.

Similar presentations


Presentation on theme: "Chapter 18 Cell Junctions, Cell Adhesion, and the Extracellular Matrix."— Presentation transcript:

1 Chapter 18 Cell Junctions, Cell Adhesion, and the Extracellular Matrix

2 A cross-sectional view of part of the wall of the intestine
Cell junctions to adjacent cells or Basal lamina Rich in ECM

3 Cell junctions: Occluding junctions--seal cells together, prevent even small molecules from leaking from one side of the sheet to the other; Anchoring junctions--mechanically attach cells and their cytoskeleton to their neighbors or to the extracellular matrix; Communicating junctions--mediate the passage of chemical or electrical signals from one interacting cell to its partner

4 The role of tight junctions in transcellular transport
The structure of a tight junction Diffusion barrier Sealing strands: a long row of transmembrane adhesion proteins Claudins Occludins ZO (zonula occludens): anchor the strands to actin cytoskeleton

5 Septate junctions: occluding junctions in invertebrates
More regular a structure A continuous band around each epithelial cell Parallele rows of junctional proteins:regular periodicity Discs-large in fly in related to ZO

6 Anchoring junction:connecting cytoskeleton to a neighbor or to the ECM
Adherens junctions and desmosomes: among cells-cadherins Focal adhesions and hemidesmosomes-integrins Actin filaments Intermediate filaments

7 Adherens junctions Actin bundles are linked via the cadherins and anchor proteins into an extensive transcellular network Adhesion belt contractile

8 Desmosomes connect intermediate filaments from cell to cell
Buttonlike Pemphigus: autoimmume disease-antibodies bind to and disrupt the desmosomes-blistering of the skin with leakage of body fluid into the loosened epithelium

9 Focal adhesion actin vinculin Muscle cells attach to
their tendons this way

10 Desmosomes and hemidesmosomes
integrins

11 Gap junction Gap! Electrical and chemical coupling

12 Summary of cell juctions in a vertebrate epithelial cell

13 Plasmodesmata are the plant gap junctions
Plant don’t need anchoring junctions

14 Cells assemble to form a tissue

15 The structure and function of cadherins
Calcium-dependent Homophilic

16 E-cadherin N-cadherin Cadherin-7 in ganglion cells from neural crest cells

17 Three ways cell-surface molecules can mediate cell-cell adhesion
Cadherin-dependent cell sorting

18 Selectins mediate transient cell-cell adhesions in the bloodstream
Calcium-dependent Carbohydate-binding proteins (lectins) Binding of white blood cell to endothelial cells

19 Immonoglobulin superfamily proteins mediate Calcium-independent cell-cell adhesion

20 Summary of the junctional and nonjunctional adhesive mechanisms

21 The repeating disaccharide sequence of dermatan
sulfate glycosaminoglycan (GAG) Negatively charged ECM: polysaccharide chains GAGs linked to protein(proteoglycans) And fibrous proteins (collagen, elastin, fibronectin, laminin)

22

23 A model of the molecular structure of a basal lamina

24 Dog aorta Covalent bonds Stretch and recoil like a rubber band Five times more extensible

25 Plant cell walls are made of polysaccharide cellulose,
the most abundant organic macromolecule on earth Long unbranched chains Of b1,4-linked glucose uints

26 Summary Three types of cell junctions: structure and function
Cell adhesion has important role in development and function Two main types of ECM molecules: proteoglycans and fibrous proteins


Download ppt "Chapter 18 Cell Junctions, Cell Adhesion, and the Extracellular Matrix."

Similar presentations


Ads by Google