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2014-03-09 18:03:02
MCDB chapter

chapter 7
Show Answers:

  1. What are the four basic glycoconjugates?
    Proteoglycan, glycoprotein, lipopolysaccharide, and glycolipid.
  2. Define proteoglycan:
    • Proteoglycan: Sugars + protein, sugars dominant.
    • Have glycosaminoglycans attached.
    • Function as a component of the extracelluar matrix.
  3. Define glycoprotein: how are the carbohydrates attached to the protein? (hint: two linkages)
    • Glycoprotein: Sugars + protein, protein dominant. found on outside of cell, part of cell to cell interaction. Found on outside of cell due to being only a large polar molecule.
    • O-linked or N-linked.
  4. Understand the differences between the N-linked and the O-linked sugars.
    • O-linked: amino acids involved are Ser or Thr
    • N-linked: amino acid involed is Asn
    • O and N are the molecules that link on the reducing end of the sugars.
  5. define lipopolysaccharides:
    • Lipopolysaccharides: Sugars + lipids, sugars dominant.
    • Function as a component of the outer membrane of gram-negative cells, target of antibodies.
    • Membrane lipid with carbohydrate as hydrophobic head group.
  6. define glycolipids:
    • Glycolipids: Sugars +lipids, lipids dominant.
    • Function to provide energy and serve as markers for cellular recognition.
    • Membrane lipid with carbohydrate as hydrophobic head group.
  7. Define glycoconjugate:
    Glycoconjugate: Non-sugar compound with covalently attached sugars. Types of glycoconjugates include proteoglycan, glycoprotein, lipopolysaccharide, and glycolipids.
  8. What are the components of glycosaminoglycans? what sulfur-containing functional geoup is common in GAG?
    Glycosaminoglycans: they are composed of repeating disaccharide units. The sulfur-containing functional group that is common in them is the sulfuryl group, esterified sulfate groups. The GAGs differ in glycosidic bonds and number of sulfuryl groups.
  9. What are the components of peptidoglycans?
    Peptidoglycan: part of bacterial cell wall. Composed of alternating N-acetylglucosamine and N-acetylmuramic acid in (B1à4) linkage.
  10. What is a proteoglycan aggregate and what is its function?
    Proteoglycan aggregates: enormous supramolecular assemblies of many core proteins all bound to a single molecule of hyaluronan. Glycoconjugate, supermolecular complexes. Core protein (aggrecan) + chondroitin sulfate + kerratan sulfate. Its function is to have binding sites for multiple extracellular matrix proteins -> matrix proteins bind to integrins -> cell migration, cell-cell adhesion, and/or signaling.
  11. Understand lectins: what they bind to, what kinds of materials the come from and how they function
    Lectins: proteins that bind sugars with high specificity and affinity and ‘read’ the sugar code. Involved in cell recognition, cell adhesion, and signaling. Used as tools for labeling and carbohydrate detection.
  12. Describe the complexity associated with the analysis of carbohydrates: what are they used for?
    • >20 different monosaccharides connected via various types of glycosidic bonds à billions of different oligosaccharides possible. Oligosaccharide sequences can be used as unique molecular recognition tags (biological bar code).
    • Used as tools for labeling and carbohydrate detection.
    • Involved in cell recognition, cell adhesion, and signaling.