MCB 2610 Lecture 9: Metabolism
25 May 2018
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Catabolism: break down and oxidation of larger molecules -> yield energy needed for anabolism !
Anabolism: biosynthesis of macromolecular cell components from smaller molecular units !
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Prokaryotes as group have very diverse metabolisms in a way that where they put their electrons:
Super valuable for global ecology : Nitrogen fixation •
Big role in carbon cycle !•
Important for fermentation they do: beer/wine, bread/ yogurt, soy sauce , cheese , industrial fermentation (Ethanol, •
methanol, butanol) !
Classification: !•
+Carbon - where does carbon come from? !
+Energy: what is used to make ATP? !
+Electron sources: reducing power -used to make ATP and for biosynthesis (fatty acids), where do electrons end up !
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Carbon !
N2= fixation : !
N2-> NH3 -> biosynthesis !•
Carbon fixation -> needed to be made available for biosynthesis: !
CO2 -> CH2O: base of terrestrial and other ecosystem (in photosynthesis) !•
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Organism that can fix carbon:
-via photosynthesis: purple bacteria , plants, cyanobacteria and other photosynthetic bacteria (purple alpha proteos - not via
oxygenic photosynthesis, green sulfur bacteria, halophiles such as archae) other means too -> autotrophs !
-CO2, methanol, formate, methane !
-Everything else can’t fix carbon and must get it from the environment in already fixed forms -> organic molecules such as
heterotrophs !
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Autotrophs - Plants/ Cyanobacteria:
Get carbon from CO2 -> fixed into 3-phosphoglycerate -> RUBISCO -> dominant enzyme on the planet. !
Energy: light !
Electrons: water !
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Heterotrophs - Human/ E. Coli/ Bacillius/ Yeast (fungi)/ Protists: !
Human: !
+Get carbon from food (organic molecules) !
+Energy from food (organic molecules) !
+Electrons from food (organic molecules) !
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Electron sources: Reducing power!
Reduced compound is usually rich with covalently bounded hydrogens. For example: C6H12O6 - glucose and other •
carbohydrates , fatty acids, H2S, NH3, H2 !
Oxidized and electrons are passed to: !•
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Losing electrons = oxidation !
Gaining electrons = reduction !
-The electrons from oxidation used for energy generation: makes hydrogen ion gradient which stores the energy and used the
energy for ATP synthesis or spinning flagella or transporting the substrate across the membranes !
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Electrons can come from one organic sources!
Organic molecules: CHO, fatty acids, proteins, DNA,....!•
-> organotrophs: humans , e.coli !
Inorganic molecules: NH3, H2S, H2, Fe +2 !•
-> lithotrophs (rocks)!
Energy sources:
Light: plants, bacteria -> use this energy to make ATP -> Phototrophs !•
Chemicals: oxidized and used via electron transport chain to make ATP -> Chemotrophs !•
Photosynthesis and chemicals are used to generate proton motive force (pmf battery). -> Make ATP and active transport and
rotate flagella !
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Plants Humans
Photolithoautrophs #########Chemoorganoheterotrophs !
En. El. Car##########En. El. Carb !
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Organism : !
Light: organic molecules for electrons !•
Organic moleculues for carbon !•
Energy from carbon !•
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->Photoorganoheterotrophs !
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bacteria that containing Methane fixes carbon: helps with hyperthermophilic environments. !
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Aerobic metabolism (E. Coli):
NAD must be generated from NADH or else glycolysis and TCA will stop
Document Summary
Catabolism: break down and oxidation of larger molecules -> yield energy needed for anabolism. Anabolism: biosynthesis of macromolecular cell components from smaller molecular units. Prokaryotes as group have very diverse metabolisms in a way that where they put their electrons: Super valuable for global ecology : nitrogen xation. Important for fermentation they do: beer/wine, bread/ yogurt, soy sauce , cheese , industrial fermentation (ethanol, methanol, butanol) Co2 -> ch2o: base of terrestrial and other ecosystem (in photosynthesis) +electron sources: reducing power -used to make atp and for biosynthesis (fatty acids), where do electrons end up. Carbon xation -> needed to be made available for biosynthesis: Via photosynthesis: purple bacteria , plants, cyanobacteria and other photosynthetic bacteria (purple alpha proteos - not via oxygenic photosynthesis, green sulfur bacteria, halophiles such as archae) other means too -> autotrophs. Everything else can"t x carbon and must get it from the environment in already xed forms -> organic molecules such as heterotrophs.
