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Peptidoglycan quiz

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  • What are the two repeating sugar units found in peptidoglycan?
    The two repeating sugar units are N-acetylglucosamine (NAG) and N-acetylmuramic acid (NAM).
  • How are NAG and NAM linked together in peptidoglycan?
    They are linked by beta-1,4 glycosidic linkages.
  • What is the main structural function of peptidoglycan in bacteria?
    Peptidoglycan provides structural support to bacterial cell walls.
  • Is peptidoglycan a branched or unbranched polysaccharide?
    Peptidoglycan is an unbranched polysaccharide.
  • What does the 'peptido' prefix in peptidoglycan refer to?
    It refers to the short peptide cross-links that connect the polysaccharide chains.
  • Which sugar unit in peptidoglycan is also found in chitin?
    N-acetylglucosamine (NAG) is found in both peptidoglycan and chitin.
  • What distinguishes NAM from NAG in peptidoglycan structure?
    NAM has a carboxylic acid group and is linked to a peptide, while NAG does not.
  • What is the thickness of the peptidoglycan cell wall in gram positive bacteria?
    The peptidoglycan cell wall in gram positive bacteria is about 250 angstroms thick.
  • How do gram positive bacteria react to the gram stain?
    Gram positive bacteria absorb the gram stain and react positively.
  • What is the thickness of the peptidoglycan cell wall in gram negative bacteria?
    The peptidoglycan cell wall in gram negative bacteria is about 30 angstroms thick.
  • What additional structure surrounds the peptidoglycan layer in gram negative bacteria?
    Gram negative bacteria have a complex outer membrane surrounding the peptidoglycan layer.
  • What makes gram negative bacteria more resistant to some antibiotics?
    Their complex outer membrane, which contains lipopolysaccharides, makes them more resistant.
  • What are lipopolysaccharides and where are they found?
    Lipopolysaccharides are polysaccharides with lipids attached, found in the outer membrane of gram negative bacteria.
  • What mnemonic can help remember the difference between gram positive and gram negative cell walls?
    Think 'positive' is thick and 'negative' is thin to remember the cell wall differences.
  • Why do gram negative bacteria need a complex outer membrane?
    They compensate for their thin peptidoglycan cell wall by having a more complex outer membrane.