MICB Lecture 3

• pili

  fine, hairlike appendages that are thinner and typically shorter than flagella, only visible in electron microscope, grow by adding protein subunits to their base
• sex pili

  many bacteria have up to 10

  they are often longer than other pili and are genetically encoded on plasmids
• monotrichous

  one flagellum
• amphitrichous

  one flagellum at each end
• lophotrichous

  cluster of flagella at one or both ends
• peritrichous

  spread over entire surface of cell
• flagella

  extend outward from plasma membrane and cell wall, in addition to motility they can be involved in attaching to surfaces or they contribute to the ability of bacterium to cause disease
• filament

  hollow, rigid cylinder constructed of subunits of protein (flagellin), ends with a capping protein, grows at its tip
• Bacterial flagellum

  proton motive force: inward flow of protons drive rotation of M and S ring

  low concentration on the outside, high on the inside

  A) filament

  B) hook

  C) L ring

  D) P

  E) MS

  F) Rod

  
• Bacterial flagellum rotation

  attractants cause counterclockwise rotation: rotation causes forward motion (run), flagella bundle on one end

  repellents cause clockwise rotation: disrupts run, causing cell to stop and tumble, flagella fly apart, cells change directions

  Runs + tumbles = random walk
• chemotaxis

  sensory system that enables microbes to move toward or away from specific chemicals
• Archaea features

  Prokaryotic

  • reproduction: asexual
  • live: terrestrial and aquatic
  • circular, dsDNA chromosomes and plasmids
  • gram pos or neg, diverse shapes
  • sizes similar to bacteria (um)
  • plasma membrane
  • no peptidoglycan
  • some have S layers instead of cell wall
  • some are motile
• Methanogenesis

  biological production of methane (potent greenhouse gas, over 25x as potent as CO2 at trapping heat), feature of archaea
• Extremophiles

  some archaea

  • thermophiles grow between 45-85C
  • hyperthermophiles grow between 85-113C
• Genus and where does it live

  Genus: Haloquadratum

  Lives in high salt environments

  
• Bacterial vs archaeal membranes

  Bacteria: bilayers

  Archaeal: bi or monolayers, have a presence of ether-linkage (in monolayers of c40 tetraethers) between glycerol and side chain
• Name/ features

  Pyrococcus furiosus

  • hyperthermophile
  • produces >50 flagella at one end of cell
  • source of Pfu polymerase for PCR