Summary: Bacteria

Read the summary and the most important questions on Bacteria

• 1 college

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• Describe the colonizaton by bacteria

  
  1. Adherence: by pili/fimbrae and outer proteins
  2. Biofilm formation: adhered bacteria embedded in a matrix of exopolysaccharides, resistant to environmental stress
  3. Invasion: via endocytosis, paracytosis or transcytosis, production of enzymes to degrade host cell membrane
  4. Toxins: induce host cell death
  - exotoxin: made by bacteria, goes out
  - endotoxin: on surface of bacteria (LPS)
  5. Serum survival: acquire nutrients from host, evade immune system

• What is quorum sensing

  the ability to detect and to respond to cell population density by gene regulation using signal molecules called autoinducers. In biofilms for example, quorum sensing is used to detect whether it is useful to perform a virulent attack.

• What is the repressor system?

  This is a negative feedback system for virulence. In presence of the signal the repressor binds and there is no transcription.

• 3 werkgroep

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• What is the function of the cytoplasmic membrane (inner membrane) of the bacterial cell envelope?

  - It separates the interior from the exterior. - All membrane-associated functions of all of the eukaryotic organelles are performed here (energy production, lipid biosynthesis, protein secretion, transport).
  - It withstands turgor pressure exerted on the plasma membrane

• What is the function of the peptidoglycans of the bacterial cell envelope?

  
  - Cell shape (exoskeleton)
  - Essential for stabilizing cell membranes against high internal osmotic pressures

• What is the function of lipoproteins in the bacterial cell envelope?

  Binds outer membrane with peptidoglycan

• What is the function of the outer membrane (Outer leaflet, beta-barrel proteins)?

  - Protective barrier
  - Contains molecules to attach to host cells or to induce an immune response
  - Passive diffusion of small molecules
  - High affinity transport of LPS
  - Important for stabilisation of the bacteria

• What is the function of lipopolysaccharide (lipoproteins) in the bacterial cell envelope?

  
  - Responsible for the endotoxic shock
  - Forms a protective barrier

• What is the function of the periplasm in the bacterial cell envelope?

  Densely packed with proteins (harmful, degradative enzymes)

• What is the function of trans envelope machines in bacterial cell envelopes?

  Transmembrane proteins required for motility, secretion and uptake