Chapter5
Chapter 5: Nutrition and Metabolism
Page 1
Overview of Nutrition and Metabolism
Page 2
Sections Covered:
Nutrition and Culture Media
Energetics and Enzymes
Bioenergetics
Catalysis and Enzymes
Oxidation-Reduction and Energy-Rich Compounds
Catabolism
Anabolism
Page 3: Nutrition and Culture Media
5.1 Nutrition
Macronutrients:
Carbon (C): ~50% of cell dry weight; backbone of biomolecules.
Oxygen (O) and Hydrogen (H): Derived from organic molecules, CO2, or H2O.
Nitrogen (N): ~12% of cell dry weight; key for amino acids and nucleic acids.
Phosphorus (P): Essential for phospholipids, nucleic acids, and ATP.
Sulfur (S): Important for amino acids, vitamins, and coenzymes.
Potassium (K+), Magnesium (Mg2+), Sodium (Na+): Required for enzyme activity and stabilization.
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Micronutrients:
Iron (Fe): Crucial for cellular respiration; exists in ferrous (Fe2+) and ferric (Fe3+) forms.
Other Metals: Cu, Mn, Mo, Ni, Se, W, Zn; required in trace amounts for enzyme activity.
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Growth Factors: Organic compounds like vitamins and amino acids needed in small amounts.
Page 7: Culture Media
5.2 Culture Media
Types of Media:
Liquid Media
Solid Media: Contains solidifying agents.
Classes:
Complex Media: Chemically undefined substances.
Defined Media: Precise chemical composition known.
Specialty Media: Selective and differential media for specific microbial growth.
Page 10: Energetics and Enzymes
5.4 Bioenergetics
Free Energy (G): Energy available to do work.
Free Energy Change (ΔG): Indicates spontaneity of reactions.
Positive ΔG: Endergonic (requires energy).
Negative ΔG: Exergonic (releases energy).
Page 12: Catalysis and Enzymes
5.5 Catalysis and Enzymes
Catalysts: Lower activation energy, increase reaction rates without affecting equilibrium.
Enzymes: Biological catalysts, typically proteins, highly specific, and rely on weak bonds.
Page 16: Redox Reactions
5.6 Redox Reactions
Energy Conservation: Through oxidation-reduction reactions.
Reduction Potential (Eo’): Tendency to gain or lose electrons; measured in volts.
Page 19: Electron Carrier: NAD
5.7 Electron Carrier: NAD
Classes of Electron Carriers:
Prosthetic Groups: Attached to enzymes.
Coenzymes: Diffusible, e.g., NAD+/NADH.
Page 21: Energy-Rich Compounds
5.8 Energy-Rich Compounds
ATP: Primary energy currency.
Long-term Storage: Insoluble polymers like glycogen and lipids.
Page 23: Catabolism
5.9 Energy Conservation
Energy Conservation Mechanisms:
Substrate-Level Phosphorylation (SLP)
Oxidative Phosphorylation
Page 25: Glycolysis
5.10 Glycolysis
Pathway: Common for fermentation and respiration of glucose; anaerobic process.
Page 29: Respiration
5.11-12 Respiration
Energy Metabolism: Involves oxidation-reduction reactions.
Fermentation vs. Respiration:
Fermentation: Uses metabolic intermediates as terminal electron acceptors.
Respiration: Uses O2 (aerobic) or other substances (anaerobic).
Page 33: ATP Synthase
Mechanism: Converts ADP + Pi to ATP using proton motive force.
Page 35: Carbon Flow in Respiration
5.13 Carbon Flow in Respiration
TCA Cycle: Also known as Krebs cycle or citric acid cycle.
Page 39: Anabolism
5.15 Biosynthesis of Sugars and Polysaccharides
Prokaryotic Polysaccharides: Synthesized from active forms of glucose.
Page 42: Biosynthesis of Amino Acids and Nucleotides
5.16 Biosynthesis of A.a. and Nucleotides
Amino Acids: Sourced from glycolysis and TCA cycle; nitrogen from inorganic sources.
Page 45: Biosynthesis of Fatty Acids and Lipids
5.17 Biosynthesis of Fatty Acids and Lipids
Fatty Acids: Synthesized two carbons at a time; involves acyl carrier protein (ACP).
Page 46: Regulation
5.18 Regulation
Modes of Regulation:
Amount: Gene, transcription, and translation level.
Activity: Temporary inactivation through covalent or noncovalent changes.
Feedback Inhibition: End product inhibits the first enzyme in the pathway.
Page 49: Covalent Modifications
Covalent Modifications: Involves attachment/removal of small molecules,