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Biochemical Pathways of Energy Metabolism Series of controlled reactions rather than in a single burst.

Metabolism b

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Page 1: Metabolism b

Biochemical Pathways of Energy Metabolism

Series of controlled reactions rather than in a single burst.

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Carbohydrate Metabolism

Glycolysis – Embden Meyerhoff Pathway

Oxidation of glucose to pyruvic acid, series of 10 reactions, each reaction catalyzed by a different enzyme

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Carbohydrate metabolism

Pentose Phosphate Pathway – hexose monophosphate shunt

Operates simultaneously with glycolysis Provides a means for the breakdown of

5 carbon sugars as well as glucose

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Carbohydrate Metabolism

EDP is still another pathway for oxidizing glucose to pyruvic acid

Yield 1 ATP

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Fermentation of Carbohydrates

Glucose Pyruvic Acid fermentation or respiration

Release energy from sugars or other organic molecules such as amino acids, organic acids, purines and pyrimidines

Does not require oxygen Does not require an electron transport

chain

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Fermentation of Carbohydrates

Uses an organic molecule as the final electron acceptor

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Fermentation

Products – ethanol and carbon dioxide Brewing and wine making are anaerobic

processes if oxygen is present further oxidation will occur

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Respiration

Is an ATP generating process in which chemical compounds are oxidized and the final electron acceptor is almost always an inorganic molecule

Electron transport chain – readily accept electrons from one compound and pass them to another

ATP generated by oxidative phosphorylation

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Respiration

Oxidize organic molecules completely to carbon dioxide

ATP yield greater in respiration than in fermentation

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Krebs Cycle

As acetyl CoA enters the Krebs cycle, CoA detaches from the acetyl group and then can pick up more acetyl groups for the next Krebs cycle

Series of redox reactions Yield 38 ATP

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Protein Catabolism

Require extracellular enzymes – proteases and peptidases

Deaminate amino acids Decarboxylation

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Lipid Catabolism

Fats fatty acids + glycerol Requires lipases Convert glycerol into dihydroxyacetone

phosphate Fatty acids catabolized by beta

oxidation

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Energy Utilization

Microbes use ATP to provide energy for the transport of substances across plasma membranes

For flagellar motion Biosynthesis of new cell components

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Biosynthesis of Polysaccharides

Bacteria synthesize glycogen from adenosine diphosphoglucose – ADPG

Synthesize capsular material

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Biosynthesis of Lipids

Microbes synthesize lipids, by uniting glycerol and fatty acids

Structural components of plasma membrane and Gram – cell wall

Lipids serve as storage forms of energy

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Biosynthesis of Amino Acids

Required for protein synthesis E. coli – synthesize all the amino acids

they need Other microbes require some preformed

aa from the environment in order to metabolize proteins

Krebs cycle source of precursors for aa

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Biosynthesis of Amino Acids

Other sources of precursors are derived from the pentose phosphate pathway and the EDP

AA building blocks for proteins (toxins)

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Biosynthesis of Purines & Pyrimidines

Sugars composing nucleotides are derived from either the PPP or the EDP

Aspartic acid, glycine and glutamine play an essential role in the biosynthesis of purines and pyrimidines

The C and N atoms derived from these aa form the backbone of the purines and pyrimidines

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Integration of Metabolism

Anabolic and catabolic reactions are integrated through a group of common intermediates

Krebs cycle – operate in both anabolic and catabolic reactions produce intermediates that lead to the synthesis of amino acids, fatty acids and glycerol – amphibolic pathways