Cell Junctions Section 5.7

Learning Objectives Compare the structures and functions of anchoring junctions, tight junctions, gap junctions, and plasmodesmata

Cell Junctions Cell junction = Structure that connects a cell to other cells Aid in cellular communication Help cells stick together to make tissues Prevent the passage of materials 4 main types Anchoring junctions Tight junctions Gap Junctions Plasmodesmata

Anchoring Junctions Found in animal cells 2 Functions: Locks cells together Found in large number in skin & tissues that experience scratching or stretching Strengthen tissues that contract Ex. Found in heart muscle Connect cytoskeleton filaments inside the cell to the ECM on the outside of the cell Allows messages from the outside environment to be received

Desmosomes Adhering Junctions

Tight Junctions Found in animal cells Prevent body fluids from leaking between neighboring cells Ex. Lining of your stomach is covered in tight junctions to keep stomach acid in your stomach Found in tissues that line body surfaces or form internal cavities

Gap Junctions Found in animal cells Make channels that connect the cytoplasm of neighboring cells Similar to plasmodesmata Can open or close in response to a stimulus (aid in communication) Found in cells that perform coordinated actions Ex. Heart muscle

Plasmodesmata Found in plant cells Open channels (tubes) that go through the cell walls Connects the cytoplasm of adjoining cells Similar to gap junctions in animal cells