MCB 11 Lec Chapter 7

• Archaea divided into two: Euryarchaeota and Crenarchaeota
• prokaryotic cell structure: no true nucleus, no membrane bound organelles
• prokaryotic cell structure: has cell wall, capsule (outermost layer), flagellum, sometimes cilia or fimbriae
• bacteria: cell wall, cytoplasmic membrane, nucleoid, cytoplasm, plasmid, ribosomes
• archae has no plasmid and ribosome
• Two very large bacteria: epulopiscium fishelsoni and thiomargarita namibiensis
• prokaryotic cell shapes: coccus, bacillus, vibrio, coccobacillus, spirillum, spirochete
• coccus = round
• bacillus = rod
• vibrio = curved rod
• coccobacillus = short rod
• spirillum = spiral
• spirochete = long, loose, hellical spiral
• cell morphologies: coccus, rod, spirillum, spirochete, budding and appendaged, filamentous
• Haloquadratum walsbyi with red fluorescent stain targeting carbon storage polymers.

  • gives the greatest ratio of surface area to volume of all known microbes (thin and rectangular)
  • green = halomucin
• H. walsbyi where green is halomucin and red is carbon storage. greatest ratio of surface area to volume. thin and rectangular.
• Cell arrangement of prokaryotic cells.

  1. Coccus = single
  2. Diplococcus = pair
  3. Tetrad = four
  4. Streptococcus = chain
  5. Staphylococcus = cluster
  6. Bacillus = single rod
  7. Streptobacillus = chain rod
• sarcinae 4D, tetrad four only
• arrangement of cocci: diplococci, tetrad, sarcinae, staphylococci
• arrangement of baccili: single, diplo, strepto, cocco, palisades (like a fence angular)
• arrangement of spiral bacteria: vibrio, spirillium, spirochete
• other shapes and arrangements of bacteria : filamentous, rectangular, star-shaped, pleomorphic
• fruiting bodies (bacteria shape)

  process: mound > fruiting body > myxospores germination > outgrowth of vegetative cells > vegetative cycle > swarming and aggregation

  
  

  or

  
  

  1. fruiting body and myxospore formation
  2. germination
  3. outgrowth of vegetative cells
  4. vegetative cycle
  5. swarming and aggregation

  
• Prokaryotic cell nutrition

  1. photoautotrophic = co2 + sun energy
  2. photoheterotrophic = inorg org materials + sun
  3. chemoautotrophic = co2 + inorg org materials
  4. chemoheterotrophic = both inorg org
• crown gall is a pathogenic fungus that causes the formation of tumours on the roots of plants
• [habitat] prokaryotes can either be pathogenic or symbiotic
• [habitat] microorg in ruminant animals, specifically in rumen of cow. grass > cellulose > glucose > microbial fermentation (fatty acids which would be nutrition for animal or co2 and ch4 waste products)
• EXTERNAL STRUCTURES to the cell:

  1. glycocalyx
  2. flagella
  3. pili/fimbriae
• [ext struct] Glycocalyx

  • outer viscous covering of fibers extending from bacterium
  • usually a viscous polysaccharide or polypeptide slime
  • not all stages / bact produce glycocalyx
  • two types: capsule and slime layer
• [glycocalyx] capsule: attached to cell wall via sugars in capsule and wall. facilitator of pathogen attachment.
• [ glycocalyx]capsule: well-organized; firmly attached to cell wall and not easily washed off
• glycocalyx slime layer

  • loosely attached to the cell wall, not exclude particles, penetratable by particles
• the slime layer (glycocalyx) consist of interlocking molecules of protein or glycoprotein that are regularly structured
• func of slime layer proteins: receptor, inhibit phagocytosis, resistance to predation, cell wall integrity, iron uptake, swimming
• importance of glycocalyx:

  1. protection against ion and pH changes and osmotic stress
  2. protection against certain enzymes
  3. protection against predacious bacteria and phagocytes
  4. enhances virulence of pathogenic bacteria
  5. adhere to environmental surfaces, colonize, and resist flushing
• [ext structure] basic structure of flagella

  1. basal body = motor
  2. hook = connects basal to filament
  3. filament = protuding outside, gumagalaw na part
• [ext structure] basic structure of flagella dif in gram positive and negative
• arrangements of flagella:

  1. monotrichous
  2. amphitrichous (both sides)
  3. lophotrichous (many one side)
  4. peritrichous (all sides)
• [ext struc] fimbriae are bristle-like projections that attach to the surface of the bacteria.
• fimbriae are more numerous and shorter, while pili are longer and less numerous per cell.