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| What are the diff. types of Cell Junctions? | Specialized attachments b/w adjacent cells; Tight Junctions (zona occludens); Adhesive Junctions; Gap Junctions |
| Specialized attachments b/w adj. cells | Provides anchoring of adj. cells to one another and provides cytoplasmic continuity b/w cells |
| Tight Junctions (Zona Occludens) | Seal cell-lined compartments; Prevent water soluble molecule from passing through b/w cells; fuse adj. plasma membranes; Maintains polarity of cell; Disrupted by reduction of calcium concentration |
| What are the two types of Adhesive junctions? | Zonula Adherens & Desmosomes. Hemidesmosomes not in terminal bar |
| Zonula Adherens | Membrane proteins CADHERIN of adj cells bind to adhere cell to each other and the actin microfilaments in cell cortex anchor adherin proteins |
| Desmosomes | Are disc shaped and Cytoplasmic Intermediate Filaments anchor the adherin family membrane proteins that bind the cell |
| Hemidesmosomes | Found in basal layer of cells. Use INTEGRIN proteins to attach cell to extracellular matrix |
| Gap Junctions | Not found in terminal bar. Does not hold cells together. Allows for passage of ions & small molecules b/w adj. cells. Cells connected by connexons made of protein Connexin. Imp. in cardiac & smooth muscle=mult. cells act as one |
| What are the 3 types of junctions found in the terminal bar? | Tight Junctions (zona occludens), Zonula adherens, desmosomes |
| What are the 3 types of surface specializations? | Microvilli, Stereocillia, and Cilia |
| What is the purpose of a surface specialization? | To incr. surface area and to move substances across cell surface |
| Microvilli | Covered w/ glycocalyx; Forms striated border; Found on apical surface of absorptive cells; Core of ACTIN filament helps maintain cell shape; NOT Motile only incr. surface area |
| Stereocilia | Long branched microvilli; Incr. surface area for TRANSPORT across membrane |
| Cilia | Motile; aka Axoneme (gen. term for cilia and flagella) Move material through the surface of cell & move cell through its environ. Composed of tubulin; requires ATP energy; motor protein is axonemal dynein |
| What is the structural composition of cilia & Microvilli? | Cilia-Tubulin protein; Microvilli-Actin protein |
