BIOL10004 Chapter Notes - Chapter 4: Basal Lamina, Endoplasmic Reticulum, Electrical Resistance And Conductance
29 Jun 2018
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Cell to cell junctions, transport and communication via gap
junctions (animals) and plasmodesmata (plants)
Intercellular connections
Plasma membranes of adjacent cells in direct contact
Connected by molecular complexes termed junctions
Junctions form between cells and extracellular matrix
Junctions can be grouped according to their function
Three types:
oTight (Occluding) Junctions: Are those where plasma membranes of adjacent cells
are tightly associated, preventing the passage of even small molecules through the
extracellular space
oAnchoring Junctions: Provide sites of attachment for the mechanical support of
tissues. They link adjacent cells, attach cells to the extracellular matrix, and form
attachment sites for fibres of the cytoskeleton
oCommunicating Junctions: are those that are specialised for chemical and electrical
communication between adjacent cells
Tight Junctions:
oLinks epithelial cells via bands of transmembrane junctional proteins
oForms barrier to free movement of molecules between cells
oEpithelial lining of intestine, tight junctions form a circumferential seal
oPermeability of junctions to small molecules varies
oServe to maintain correct location of different membrane proteins
Anchoring Junctions:
oProvide mechanical support
oIncluding desmosomes, hemi-desmosomes and adherents junctions
oDesmosomes:
Cytoplasmic thickenings either side of junction
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Document Summary
Cell to cell junctions, transport and communication via gap junctions (animals) and plasmodesmata (plants) Plasma membranes of adjacent cells in direct contact. Junctions form between cells and extracellular matrix. Junctions can be grouped according to their function. Tight (occluding) junctions: are those where plasma membranes of adjacent cells are tightly associated, preventing the passage of even small molecules through the extracellular space: anchoring junctions: provide sites of attachment for the mechanical support of tissues. They link adjacent cells, attach cells to the extracellular matrix, and form attachment sites for fibres of the cytoskeleton o. Communicating junctions: are those that are specialised for chemical and electrical communication between adjacent cells. Links epithelial cells via bands of transmembrane junctional proteins. Forms barrier to free movement of molecules between cells. Epithelial lining of intestine, tight junctions form a circumferential seal. Serve to maintain correct location of different membrane proteins o o o o o. Including desmosomes, hemi-desmosomes and adherents junctions: desmosomes:
