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11. Microbial metabolism
Metabolism - all chemical reactionsoccur in the cell. Flow of energy and
the participation of enzymes makemetabolism possible.
- divided into two:
a) anabolism - synthesis of complexmolecules from simpler ones with theinput of energy.
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b) catabolism - larger and morecomplex molecules are broken down
into smaller/simple molecules with therelease of energy.
- some of this energy can be used in
anabolism
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Nutritional patterns among organisms
phototrophs - use light as their primary
energy source.autotrophs - self feeders, use C sourcefrom CO2
Chemotrophs - use oxidation-reductionof inorganic/organic compounds forenergy
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Heterotrophs - feeders on others, use Csource from organic compounds.
Photoautotrophs - use light as a sourceof energy and CO2 as their chief sourceof C.
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Photoheterotrophs - use light as asource of energy , use organic
compounds eg: alcohols, fatty acids,other organic acids and CHO as sourceof C.
Chemoautotrophs - used electron fromreduced inorganic compounds as asource of energy and they use CO2 as
they principal source of C. Eg, inorganicsource of ener : H S S H NO -
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Chemoheterotrophs - use electronsfrom hydrogen atoms in organic
compounds as their energy source.
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Biochemical pathways of energyproduction:
1. Carbohydrate metabolisma)glycolysis(Embden-Meyerhofpathway)
b)Entner-Duodoroff(EDP) pathwayc)Pentose phosphate pathway (hexosemonophosphate shunt)
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2. Fermentation of carbohydrates
3. Respiration:
aerobic respiration : Krebs cycle and theelectron transport chain (ETC)
anaerobic respiration
4. Lipid catabolism
5. Protein catabolism
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Biochemical pathways of energyutilization (anabolism)
biosynthesis of polysaccharide:The C atoms required to synthesizeglucose are devised from the
intermediate produced during processessuch as glycolysis.
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From glucose to glycogen, the glucosemust be phosphorylated to glucose -6-
phosphate. A molecule of ATP is thenadded to form ADPG (adenosinediphosphoglucose).
Using UTP as a source of E and G6P,animals synthesize glycogen from UDPG
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UDPNAc is a key starting material in thebiosynthesis of peptidoglycan which is
formed from fructose -6- phosphateand uses UTP.
biosynthesis of lipids - eg: cholesterol,
waxes, carotenoids, energy storage,structural components of biologicalmembranes
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Cells synthesize fats by joining glyceroland fatty acids
The glycerol portion is deviced fromdihydroxyacetone phosphate ( anintermediate formed during glycolysis)
Fatty acids are built up when 2Cfragments of acetlyCoA are successivelyadded to each other.
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biosynthesis of amino acids - aa arebuilding blocks for protein synthesis
proteins play major roles in the cell asenzyme, structural components, toxins.
The joining of aa requires energy and
involves dehydration synthesis.Integration of metabolism