Extracellular matrix and cellular junction

Extracellular matrix and cellular junction - THE...

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THE EXTRACELLULAR MATRIX AND CELLULAR JUNCTIONS pp.703-717 LECTURE 19
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1. Extracellular Structures: -Virtually every cell contains an exterior fibrillar material consisting mainly of macromolecules that are secreted by the cell . Animal cells have an ECM that takes on a variety variety of forms and plays important roles cell division cell division , , motility motility , , differentiation differentiation , , and and adhesion adhesion . -Plants, fungi, algae and prokaryotes have CELL WALLS as an extracellular structures (also in many examples there is a clear fibrous ECM) 2. The ECM of Animal Cells : -The ECM of animal cells is diverse . Bone Bone : consists largely of a rigid extracellular matrix that contains a tiny number of interspersed cells Cartilage Cartilage : another tissue constructed almost entirely of matrix materials, although the matrix is much more flexible than bone. Connective tissue Connective tissue : having a gel-like ECM with numerous interspersed cells, e.g., fibroblast.
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A cross-section through connective tissue under the epithelium.
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- Though diverse, the ECM of animal cells all consist of three classes three classes of molecules: (i) (i) Structural proteins Structural proteins : Collagens and elastins provide strength and flexibility * Collagen : --A large family of closely related proteins that are the most abundant component of the animal ECM; indeed it is the most abundant protein in vertebrates (20% to 30% of total body protein). Collagen Collagen form fibers with high tensile strength and thus account for much of the strength of the ECM. -- -- Collagen Collagen is secreted by several types of connective- tissue cells including FIBROBLASTS. --Prominent in connective tissues like tendons and ligaments. Collagen fibrils are organized into bundles Collagen fibrils in skin are arranged in a plywood pattern
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* Elastins : Provides elasticity, required in lungs and arteries. Over time collagens are increasingly crosslinked and inflexible, and elastins are lost from the skin; i.e., aging. -- Function: provide elasticity to tissues -- Appearance: fibrous in nature when viewed with the electron microscope.
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(ii) Protein (ii) Protein -polysaccharide complexes (= polysaccharide complexes (= proteoglycans proteoglycans ) ) --Provide the gel-like matrix in which the structural molecules are embedded, i.e.,
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This note was uploaded on 10/10/2009 for the course BIO 351 taught by Professor Oberstein during the Spring '08 term at ASU.

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Extracellular matrix and cellular junction - THE...

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