Intercellular Junctions AP Biology Ms. Oldendorf Chapter 6 - Cells

Intercellular Junctions (cells are connected to each other!!) Fundamental to the interactions between cells Fundamental to the interactions between cells allow coordination of activities of individual cells in a system Enables each system to function as an integrated whole

Plant Cells have plasmodesmata - connect the living contents of adjacent cells - channels in the cell wall through which strands of cytoplasm pass

Plasmodesmata… Enable… - the transport of proteins, ions, and water - communication - transfer of chemical signals

Animal Cells (have 3 different kinds of junctions) 1) Tight junctions - membrane proteins interlock –Membranes of neighboring cells are fused –Form a continuous “belt” around a cell

Tight Junctions Prevents… -leakage of extracellular fluid across a layer of epithelial cells -passage of molecules and ions through the space between cells. Example: junction between epidermis of the skin

2) Desmosomes, (anchoring junction) - intermediate filaments “sew” membranes together

Desmosomes – –Fasten cells together into strong sheets  Muscle cells are held together by desmosomes.  ? So What does it mean when we say a muscle is torn?

Gap junctions- channels align allowing materials to flow between cells Gap junctions- channels align allowing materials to flow between cells

Gap Junctions allows for communication through exchange of materials and transmission of electrical impulses Cytoplasmic channels between adjacent cells Cytoplasmic channels between adjacent cells –Salts, sugars, AAs, etc. can pass through