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Concept 27.2


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Concept 27.2

  1. 1. Alex, Maya, Michelle
  2. 2.  Nutritional diversity is greater in prokaryotes than eukaryotes Phototrophs-organisms that obtain energy from light Chemotrophs-those that obtain energy from chemicals Autotrophs-organisms that only require CO2 as a carbon source Heterotrophs-organisms that require at least 1 other organic nutrient to make other organic compounds
  3. 3.  Photosynthetic organisms Capture light energy and use it to drive the synthesis of organic compounds from CO2 Ex: Cyanobacteria, plants and algae
  4. 4.  Also only require CO2 as a carbon source and oxidize inorganic substances like ammonia, hydrogen sulfide Mode of nutrition unique to certain prokaryotes Ex: Sulfolobus
  5. 5.  Use light energy but must get carbon in an organic form Used by some marine prokaryotes Ex: Rhodobacter and Chloroflexus
  6. 6.  Their energy source is organic compounds and they require organic carbon Many prokaryotes, fungi, animals and some plants use this Ex: Clostridium
  7. 7.  Obligate aerobes: use O2 for cellular respiration—cannot grow without it Facultative anaerobes: use O2 if present but can grow by fermentation in an anaerobic environment Obligate anaerobes: poisoned by O2; some live exclusively by fermentation
  8. 8.  Other obligate anaerobes extract chemical energy by anaerobic respiration—substances other than O2 accept electrons at the “downhill” end of electron transport chain
  9. 9.  Some prokaryotes convert atmospheric nitrogen (N2) to ammonia (NH3) This „fixed‟ nitrogen is incorporated into amino acids and other organic molecules
  10. 10.  Cooperation: working together Some proks can‟t use resources by themselves ◦ No specialized organelles! Cooperation between specialized cells Exchange of metabolic products
  11. 11. Ex. Cyanobacteria Anabaena can photosynthesis + nitrogen fix  Photosynth. produce O2, inactives nitrogen fixing enzymes  Live in colonies  Most carry out photosynth., others nitrogen fix  Heterocytes = “other cells” (nitrogen-fix)  Heterocytes surrounded by cell wall, inhibits O2 entry  Transport between cells  FUNCTION OF CONCENTRATION GRADIENTS AND CELL SPECIALIZATION!!!!!
  12. 12.  Biofilm = surface-coat colonies w/ metabolic cooperation Signaling molecules Channels between cells allow flow of nutrients Other species can cooperate as well