L1 prokaryotic cells

• define a prokaryotic cell

  simple in structure but biochemically diverse
• archaea often live in very extreme environments
• bacteria have enormous medical and economic importance
• what size are bacteria?

  1-2 microns
• what size are viruses?

  10-200nm
• what size are eukaryotic cells?

  10-100 microns
• archaea are often described as extremophiles
• thermophile example

  taq DNA polymerase from Thermus aquaticus
• bacteria have a peptidoglycan in their cell wall
• prokaryotic cell: no nucleus, no membrane bound organelles, smaller ribosomes, cel wall made of peptidoglycan, have flagella, pilli (hair-like structure)
• pilli are involved in:

  adhering to substrates and exchange of genetic information
• circular DNA AKA

  plasmids
• plasma membrane infoldings instead of membrane bound organelles
• flagellum in prokaryotes:

  rotary motor, energy generated by proton gradient
• shapes of bacteria:

  spherical (cocci), rod shaped (bacilli), helical (spirochetes)
• gram positive bacteria have thick layer of peptidoglycan
• gram negative has thin peptidoglycan layer

  so is more resistant to antibiotics which mainly target peptidoglycan
• gram positive cell wall strucutre:

  • peptidoglycan cell wall on top of plasma membrane
• gram negative cell wall structure:

  • outer membrane
  • periplasmic gel made of peptidoglycan
  • plasma membrane below
• biotechnology of bacteria:

  • medical
  • agricultural
  • environmental
  • industrial
• prokaryotes modes of nutrition:

  • chemoautotrophs
  • chemoheterotrophs
  • photoautotrophs
  • photoheterotrophs
• eukaryotes modes of nutrition:

  • photoautotrophs
  • chemoheterotrophs
• what does autotroph mean?

  producers- make their own food
• what does heterotrophs mean?

  consumers- consume producers/other consumers
• viruses are not eukaryotes, prokaryotes, archaea or bacteria
• viruses cannot self repair, have no energy transduction system
• types of viruses:

  filamentous, spheroid, enveloped, tailed spheriod
• filaments

  tube like viruses
• envelope virus is bound by a membranous envelope
• spheroid viruses are usually organised into multisided geometric shape