Cell Junctions Flashcards
4 types of tissue
Epithelial
Connective
Muscular
Nervous
Fibroblasts
Produce connective tissue
Secretes collagen
Bone
Collagen and mineralization
Collagen
20% of body’s protein mass
Fibers are placed at 90 degree angles to each other- strength (like plywood)
Procollagen
Fibroblasts secrete this
Proteases break it down into collagen
Integrins
Link collagen to cells
Used in binding and signaling
Membrane-spanning protein
Fibronectin
Link collagen to cells
Secreted protein
Proteoglycan
Protein that has glycosaminoglycan (GAG) associated with it
Glycosaminoglycan (GAG)
Present in connective tissue Attracts water (polar)- cushioning
GAGs in cartilage
Chondroitin sulfate (looks like spines growing off of core protein) Hyaluronan (main molecule that has core proteins and link proteins attached to it)
Basal lamina
Connects epithelial cells to the extracellular matrix
Cadherins
Link like cells together
Requires calcium to adhere molecules
e-Cadherins
Link epithelial cells
Tight junctions
Form a seal between cells: barrier for molecules
Give cells polarity
Proteins: claudin and occludin (interlock adjacent cells)
Adhesive junctions
Adherens junctions and desmosomes
Adherens junctions
Join an actin bundle in one cell to another actin bundle in an adjacent cell
Actin and cadherin: adhesion belt
Contraction
Desmosomes
Join intermediate filaments in one cell to intermediate filaments in another cell
Intermediate filaments and cadherins
Hemidesmosomes
Cell to extracellular matrix junction
Anchor intermediate filaments in a cell to the basal lamina
Integrins span the membrane (inside cell- linked to keratin, an intermediate filament; outside cell- linked to laminin and collagen
Gap junctions
Form channels that allow small water-soluble molecules to pass from cell to cell
Linkage of cytoplasm and adjacent cells
Connexon (protein that composes these) forms a hollow channel between adjacent cells
