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Eduncle posted an MCQ
December 30, 2019 • 16:13 pm 0 points
  • CSIR NET
  • Life Sciences

The extracellular matrix (ECM) is a complex combination of secreted proteins that is involved in holding cells and tissues together. The components of ECM form a network by binding to each other and communicate with cells by binding to adhesion receptors on the cell surface. ECM comprises mainly two classes of macromolecules, proteoglycans and very high molecular weight large proteins.
    Which one of the following statements regarding ECM constituents is INCORRECT ?

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    Eduncle Best Answer

    Glycosaminoglycans (GAGs) are large linear (UNBRANCHED) (hence statement 2 is incorrect) polysaccharides constructed of repeating disaccharide units with the primary configurations containing an amino sugar (either GlcNAc or GalNAc) and an uronic acid (either glucuronic acid and/or iduronic acid). There are five identified glycosaminoglycan chains : Hyaluronan, Chondroitin, Dermatan, Heparin/heparan, Keratan (Hence Statement 3 is correct). Proteoglycans consist of a core protein and one or more covalently attached glycosaminoglycan chains. Virtually all mammalian cells produce proteoglycans and secrete them into the ECM, insert them into the plasma membrane, or store them in secretory granules. Hence statement 1 is correct. The major components of the ECM are fibrillar proteins that provide tensile strength and elasticity (e.g., various collagens and elastins), adhesive glycoproteins (e.g., fibronectin, laminins, and tenascins), and proteoglycans.
            Hence statement 4 is also correct.

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