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Microbial Metabolism and Enzymes

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Termini in questo insieme (21)

  • What is metabolism?

    Metabolism is the sum of all chemical reactions in a cell, including catabolism and anabolism.

  • Define catabolism.

    Catabolism releases energy by breaking down molecules, storing energy as ATP.

  • Define anabolism.

    Anabolism uses energy from ATP to synthesize macromolecules needed by the cell.

  • What role does ATP play in metabolism?

    ATP stores energy released by catabolism and supplies energy for anabolic reactions.

  • What are enzymes and their function?

    Enzymes are biological catalysts that speed up chemical reactions by lowering activation energy without being permanently changed.

  • What is the active site of an enzyme?

    The active site is the specific region on an enzyme where substrate molecules bind.

  • What is a holoenzyme?

    A holoenzyme consists of an apoenzyme (protein part) plus its cofactor (nonprotein helper).

  • What are cofactors and coenzymes?

    Cofactors are nonprotein enzyme helpers; organic cofactors are called coenzymes, e.g., NAD+ and FAD.

  • How are enzymes named?

    Enzymes usually end in ase and are named based on the reaction type or substrate involved.

  • Difference between exoenzymes and endoenzymes?

    Exoenzymes are secreted outside the cell to break down large molecules; endoenzymes function inside the cell.

  • How does temperature affect enzyme activity?

    Increasing temperature speeds reactions up to an optimum point; high temperatures cause enzyme denaturation and loss of function.

  • How does pH affect enzyme activity?

    Each enzyme has an optimum pH; extreme acidic or basic conditions denature enzymes and reduce activity.

  • Effect of substrate concentration on enzyme activity?

    Increasing substrate concentration increases reaction rate until all enzyme active sites are saturated, reaching maximum velocity.

  • What are competitive and noncompetitive enzyme inhibitors?

    Competitive inhibitors bind the active site; noncompetitive inhibitors bind elsewhere, changing enzyme shape and function.

  • What is feedback inhibition?

    Feedback inhibition is when the end product of a pathway binds an enzyme to shut down the pathway, regulating metabolism.

  • Define oxidation and reduction in biological systems.

    Oxidation is loss of electrons or hydrogens; reduction is gain of electrons or hydrogens; these paired reactions are called redox reactions.

  • What is glycolysis and its main products?

    Glycolysis breaks down glucose into 2 pyruvic acids, producing 2 net ATP and 2 NADH molecules.

  • What happens in the intermediate (preparatory) step of respiration?

    Pyruvic acid is converted to acetyl CoA, producing 1 CO2 and 1 NADH per pyruvate, preparing for the Krebs cycle.

  • What are the main outputs of the Krebs cycle?

    The Krebs cycle produces 1 ATP, 3 NADH, 1 FADH2, and 2 CO2 per acetyl CoA molecule.

  • Describe the electron transport chain's role in ATP production.

    Electrons from NADH and FADH2 pass through the chain, pumping protons to create a gradient used by ATP synthase to generate ATP by chemiosmosis.

  • What is fermentation and its ATP yield?

    Fermentation regenerates NAD+ from NADH without oxygen, producing 2 ATP per glucose and various organic end products.