Bacteria structure, function and microscopy

• What is the primary structure of the cytoplasmic membrane in bacteria?

  Phospholipid bilayer
• What lipid is specifically mentioned as part of the bacterial cytoplasmic membrane?

  Phosphatidylethanolamine
• How are the cytoplasmic membranes of bacteria strengthened?

  By hopanoids
• What is a key difference between archaeal membranes and bacterial membranes?

  Archaeal membranes are more permeable
• What is the main component of the bacterial cell wall?

  Peptidoglycan (murein)
• What percentage of the cell wall can peptidoglycan constitute in gram-positive bacteria?

  Up to 90%
• What percentage of the cell wall can peptidoglycan constitute in gram-negative bacteria?

  About 10%
• What drives peptidoglycan polymerization and crosslinking in gram-negative bacteria?

  PBP3 (septum divisome) and PBP2 (elongation-elongasome)
• What unique structure do porins have?

  Beta sheets forming beta barrels
• What is the function of porins in the outer membrane?

  Allow molecules to cross to the periplasm
• What type of molecules do specific transporters bring into the cytoplasm?

  Amino acids, sugars, and ions
• What is a characteristic of the second lipid bilayer in gram-negative bacteria?

  Contains large polysaccharide content
• What is the diffraction limit of light microscopy?

  250 nm
• What does the Gram stain exploit?

  The differences in bacterial structure
• Why is the Gram stain considered a differential stain?

  It doesn't stain all cells the same color
• What are the roles of capsules in bacteria?

  • Can be polysaccharides or proteins
  • Play a role in pathogenesis
  • Involved in biofilm formation
• Where can biofilms form?

  • On solid substrates in moisture
  • On soft tissue surfaces in organisms
  • At liquid-air interfaces
• What are fimbriae and pili made of?

  Proteinaceous material
• What roles do fimbriae and pili play in bacteria?

  Pathogenesis, biofilms, and conjugation
• What type of motility do fimbriae and pili facilitate?

  Twitching motility
• What is the structure of flagella in bacteria?

  Helical in shape

  multimeric protein complex traversing both inner and outer membranes
• What do flagella enable bacteria to do?

  Swim in liquid environments
• How do Mot proteins contribute to flagellar movement?

  Protons flowing through them cause spinning
• What percentage of the E. coli genome encodes motility-related proteins?

  Nearly 5%
• What is the dormant stage of a bacterial life cycle called?

  Endospores
• What are the key features of endospores?

  • Dormant stage of bacterial life cycle
  • Resistant to extreme conditions
  • Can germinate into active bacteria