Chapter 27

• Prokaryotes:

  • Unicellular
  • Make up the domains: Bacteria and Archaea
• Common Shapes of Prokaryotes:

  • Spherical - Cocci
  • Rod - Bacilli
  • Spiral - Spirochetes
• Peptidoglycan

  • Used in most bacterial cell walls
  • Archaeal cells lack this
• Gram Staining:

  • A stain is applied to a cells peptidoglycan
  • The thickness determines the stain color
• Gram Positive

  • Stains Purple
  • Thick layer of peptidoglycan
• Gram Negative

  • Stains Pink
  • Thin Layer of peptidoglycan
• Capsules

  • Surrounds the cell wall
  • Sticky
  • Protects the cell
  • Helps cell adhere to surfaces
• Endospores

  • Thick Coated, resistant cell within the bacterial cell
  • Made when the cell is exposed to harsh conditions
• Flagella

  • Allows for taxis - directed movement towards or away from a stimulus
• Horizontal gene transfer - a form of genetic recombination, where DNA is combined from different sources.

  • Transformation - when DNA is taken from the external environment
  • Transduction - bacteriophages carry genetic info from one host cell to another
  • Conjugation - DNA is transferred between two prokaryotic cells via a sex pilus
• Nutrition:

  • Phototroph - organisms that obtain energy from light
  • Chemotroph - organisms that obtain energy from chemicals
  • Autotroph - organisms that make their own food by using compounds as a carbon source
  • Heterotroph - organisms that require at least one organic nutrient to make organic compounds for energy
• Oxygen:

  • Obligate aerobe - must have O2 for cellular respiration; cannot grow without oxygen
  • Obligate anaerobe - O2 is lethal for these organisms; lives exclusively by fermentation
  • Facultative anaerobe - can use O2 if present, but can also carry out fermentation or anaerobic respiration without it
  • Microaerophile - only likes small concentrations of oxygen
• Label the following based on oxygen requirements:

  A) Obligate aerobes

  B) Obligate anaerobes

  C) Facultative anaerobes

  D) microaerophiles

  
• Which Domain of life is the most diverse?

  Bacteria
• The largest bacterium, can be seen with the naked eye

  Thiomargarita namibiensis
• Causes stomach ulcers. Barry Marshall drank a culture to prove this was the case.

  Helicobacter pylori
• Found in the soil. Used to develop antibiotics.

  Streptomyces spp.
• Types of extremophiles:

  • Halophiles - salt loving
  • Thermophiles - hot loving
  • Psychrophiles - cold loving
  • Mesophiles - middle loving
• Symbiosis


  An ecological relationship between organisms of 2 different species that live together in close association
• Symbiont


  a smaller participant in a symbiotic relationship, living in or on another organism
• Host


  the larger participant in a symbiotic relationship
• Mutualism


  Symbiotic relationship in which both parties benefit
• Commensalism


  Symbiotic relationship in which one party benefits and the other is neither harmed not benefitted
• Parasitism 


  Symbiotic relationship in which one party (parasite) benefits and the other (host) is harmed
• A fungal species that impacts the central nervous system of ants

  Ophiocordyceps