Bacterial Structures

Question 1

give the chemical composition and function of flagellum

Answer 1

• composition
  
  • proteins
• function
  
  • motility

Question 2

give the chemical composition and function of pilus/fimbria

Answer 2

• composition
  
  • glycoprotein
• function
  
  • mediate adherence of bacteria to cell surface
  • sex pilus forms during conjugation

Question 3

give the chemical composition and function of spore

Answer 3

• composition:
  
  • keratin like coat
  • dipcolinic acid
  • peptidoglycan
  • DNA
• function:
  
  • gram + only
  • survival: resist dehydration, heat chemicals

Question 4

give the chemical composition and function of capsule

Answer 4

• composition
  
  • organized, discrete polysaccharide layer
    
    • except poly D glutamate on B anthracis
• function
  
  • protects against phagocytosis

Question 5

give the chemical composition and function of glycocalyx

Answer 5

• composition
  
  • loose network of polysaccharides
• function
  
  • mediates adherence to surfaces, espcially foreign surfaces
    
    • ie. indwelling catheters

Question 6

give the chemical composition and function of outer membrane

Answer 6

• composition
  
  • outer leaflet: contains endotoxin (LPS/LOS)
  • embedded proteins: porins and other outer membrane proteins (OMPs_
  • inner leaflet: phospholipids
• function
  
  • gram - only
  • endotoxin: lipid A induces TNF and IL-1
    
    • O polysaccharide component is antigenic
  • most OMPs are antigenic
  • porins: transport across outer membrane

Question 7

give the chemical composition and function of periplasm

Answer 7

• composition
  
  • space b/c cytoplasmic membrane and outer membrane in gram - bacteria
  • peptidoglycan in the middle
• function:
  
  • gram - only
  • accumulate components exiting gram - cells, including hydrolytic enzymes (ie. beta lactamases)

Question 8

give the chemical composition and function of cell wall

Answer 8

• composition:
  
  • peptidoglycan is a sugar backbone with peptide side chains cross linked by transpeptidase
• function:
  
  • net like structure gives rigid support
  • protects against osmotic pressure damage

Question 9

give the chemical composition and function of cytoplasmic membrane

Answer 9

• composition:
  
  • phospholipid bilayer sac with embedded proteins (ie. Penicillin binding proteins [PBPs]) and other enzymes
  • lipoteichoic acids (gram + only) extend from membrane to exterior
• function:
  
  • site of oxidative and transport enzymes
    
    • PBPs involved in cell wall synthesis
  • lipoteichoic acids induce TNF and IL-1

Question 10

what components of cell walls are unique to gram + bacteria?

Answer 10

• lipoteichoic acid

Question 11

what components of cell walls are unique to gram - bacteria?

Answer 11

• porin
• endotoxin/LPS
• periplasmic space–beta lactamase location

Question 12

waht components of cell walls are common to both gram - and gram + bacteria?

Answer 12

• flagellum
• pilus
• capsule
• cell wall
  
  • thinner for gram -
• peptidoglycan
• cytoplasmic membrane