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Biochemistry 9

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Termini in questo insieme (20)

  • Define monosaccharide, disaccharide, oligosaccharide, polysaccharide
    Monosaccharide: simple sugars with 3-9 carbons.
    Disaccharide: 2 linked monosaccharides.
    Oligosaccharide: several linked monosaccharides.
    Polysaccharide: polymer of many saccharide units.
  • Difference between aldoses and ketoses
    Aldoses have an aldehyde group; ketoses have a ketone group.
  • What are D- and L- sugars?
    Stereoisomers differing in configuration at the asymmetric carbon farthest from the carbonyl; D has −OH on right, L on left in Fischer projection.
  • What are anomers and how are they formed?
    Isomers differing at the anomeric carbon formed by cyclization creating a new chiral center; designated as α or β.
  • Explain mutarotation
    The process of interconversion between α and β anomers in solution.
  • Difference between furanose and pyranose rings
    Furanose: five-membered ring formed by C4–OH reacting with C1.
    Pyranose: six-membered ring formed by C5–OH reacting with C1.
  • Identify the reducing end of saccharides
    The end with a free anomeric carbon capable of opening to an aldehyde or ketone, allowing reduction.
  • What is Fehling’s reaction used for?
    A test using alkaline Cu2+ to detect reducing sugars by forming a red precipitate.
  • Structure and function of sucrose, lactose, and maltose
    Sucrose: glucose + fructose, non-reducing.
    Lactose: glucose + galactose, reducing sugar.
    Maltose: two glucose units, reducing sugar.
  • Compare starch, glycogen, and cellulose
    Starch: plant energy storage, mix of amylose and amylopectin.
    Glycogen: animal energy storage, highly branched.
    Cellulose: plant structural polysaccharide, β(1→4) linked glucose.
  • Difference between amylose, amylopectin, and glycogen
    Amylose: unbranched α(1→4) glucose polymer.
    Amylopectin: branched α(1→4) with α(1→6) branches.
    Glycogen: similar to amylopectin but more frequent and shorter branches.
  • What are N-linked and O-linked glycans?
    N-linked: attached to asparagine amide side chain.
    O-linked: attached to serine or threonine hydroxyl side chains.
  • Role of carbohydrates in biological systems
    Energy metabolism and storage, molecular recognition, cellular protection, adhesion, lubrication, and structural maintenance.
  • What are glycosaminoglycans?
    Polysaccharides with repeating disaccharide units, often sulfated, functioning as lubricants and structural components.
  • Describe peptidoglycan structure and function
    Bacterial cell wall polymer of alternating N-acetylglucosamine and N-acetylmuramic acid crosslinked by peptides.
  • How does penicillin affect peptidoglycan synthesis?
    Inhibits crosslinking enzymes, weakening bacterial cell walls.
  • What is the significance of glycoproteins?
    Proteins covalently linked to oligosaccharides; involved in protein distribution, cell adhesion, and recognition.
  • Explain the ABO blood group antigens
    Carbohydrate antigens on red blood cells; A has GalNAc transferase, B has Gal transferase, AB has both, O has neither.
  • What is erythropoietin (EPO) and its glycosylation role?
    Hormone stimulating red blood cell production; glycosylation stabilizes EPO and prolongs its half-life.
  • How does influenza virus neuraminidase function and its inhibition?
    Cleaves sialic acid from host cells to release new virions; inhibited by Tamiflu, a sialic acid analog.