11. microbial metabolism

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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