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Microbiology Metabolism and Microbial Physiology

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  • What is metabolism?

    Metabolism is the sum of all chemical reactions in a cell, including both energy-releasing and energy-consuming processes.

  • Define anabolism and catabolism.

    Anabolism builds complex molecules from simpler ones, consuming energy. Catabolism breaks down complex molecules into simpler ones, releasing energy.

  • What are the three types of ATP phosphorylation?

    Substrate-level phosphorylation, oxidative phosphorylation, and photophosphorylation are the three types of ATP phosphorylation.

  • Explain apoenzyme, cofactor, coenzyme, active site, and substrate in enzymes.

    Apoenzyme is the protein part of an enzyme. Cofactor is a non-protein component needed for activity. Coenzyme is an organic cofactor. Active site is where substrate binds. Substrate is the molecule acted upon.

  • How does temperature affect enzyme activity?

    Enzyme activity increases with temperature up to an optimum, then decreases due to denaturation.

  • How does pH influence enzyme activity?

    Each enzyme has an optimal pH; deviations can reduce activity by altering enzyme shape or charge.

  • What is the effect of substrate concentration on enzyme activity?

    Increasing substrate concentration increases enzyme activity until the enzyme becomes saturated.

  • Differentiate competitive and noncompetitive inhibition.

    Competitive inhibitors bind the active site, blocking substrate. Noncompetitive inhibitors bind elsewhere, changing enzyme shape.

  • Name the three stages of aerobic glucose catabolism.

    Glycolysis, Krebs cycle, and electron transport chain are the three stages of aerobic glucose catabolism.

  • What are the substrates and products of glycolysis?

    Substrate: glucose. Products: 2 pyruvate, 2 ATP (net), 2 NADH.

  • Summarize the Krebs cycle products.

    Produces CO2, NADH, FADH2, and 2 ATP (or GTP) per glucose molecule.

  • What is the role of the electron transport chain (ETC)?

    ETC transfers electrons to oxygen (aerobic) or other acceptors (anaerobic), creating a proton gradient for ATP synthesis.

  • Contrast electron transport in aerobic vs anaerobic respiration.

    Aerobic uses oxygen as final electron acceptor; anaerobic uses other molecules like nitrate or sulfate.

  • Identify four classes of electron carriers in ETC.

    Flavoproteins, cytochromes, iron-sulfur proteins, and quinones are four classes of electron carriers.

  • What is chemiosmosis in oxidative phosphorylation?

    Movement of protons across membrane drives ATP synthase to produce ATP from ADP and Pi.

  • Describe glycolysis via the EMP pathway.

    EMP pathway converts glucose to pyruvate, producing 2 ATP (net) and 2 NADH molecules.

  • How does fermentation differ from respiration?

    Fermentation regenerates NAD+ without an electron transport chain; respiration uses ETC and produces more ATP.

  • How are biochemical tests used to identify bacteria?

    Tests detect metabolic enzymes and products to differentiate bacterial species based on biochemical capabilities.

  • Compare catabolism of lipids and proteins for energy.

    Lipids break down into glycerol and fatty acids; proteins into amino acids, both entering metabolic pathways for energy.

  • Compare photosynthesis in prokaryotes and eukaryotes.

    Both convert light to chemical energy, but prokaryotes lack chloroplasts and have different pigments and pathways.

  • What are the reactants and products of the Calvin-Benson cycle?

    Reactants: CO2, ATP, NADPH. Products: glucose and other carbohydrates.

  • How to determine if a microorganism forms a capsule?

    Use capsule staining and microscopy to visualize the capsule surrounding the cell.

  • What is the pure culture technique?

    Method to isolate single colony-forming units to obtain a pure microbial culture.