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Energy, Enzymes, and Metabolism in General Biology

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Termini in questo insieme (20)

  • What is metabolism?

    Metabolism is the collection of all enzymatic reactions that occur in an organism, including both catabolic and anabolic pathways.

  • Define catabolism and anabolism.

    Catabolism breaks down molecules and releases energy. Anabolism builds macromolecules and consumes energy.

  • What is the first law of thermodynamics?

    Energy cannot be created or destroyed; it is conserved in the universe.

  • What does the second law of thermodynamics state?

    Every energy transfer increases the entropy (disorder) of the universe; some energy is lost as heat.

  • What is free energy (G) in biological systems?

    Free energy is the portion of a system's energy that can perform work, calculated as \(\Delta G = \Delta H - T\Delta S\).

  • Difference between exergonic and endergonic reactions.

    Exergonic reactions release energy (ΔG < 0). Endergonic reactions require energy input (ΔG > 0).

  • What is ATP and its role in cellular work?

    ATP (adenosine triphosphate) is the main energy currency of the cell, coupling exergonic reactions to endergonic cellular work.

  • How does ATP hydrolysis power cellular processes?

    Hydrolysis of ATP releases energy by breaking a phosphate bond, which drives mechanical, transport, and chemical work.

  • What is activation energy (EA)?

    Activation energy is the energy barrier that must be overcome for a chemical reaction to proceed.

  • How do enzymes affect activation energy?

    Enzymes lower the activation energy, speeding up reactions without changing the overall ΔG.

  • What is the active site of an enzyme?

    The active site is the specific region where substrates bind and the catalytic reaction occurs.

  • Explain the induced fit model of enzyme action.

    Substrate binding induces a shape change in the enzyme, enhancing substrate binding and catalysis.

  • What are cofactors and coenzymes?

    Cofactors are inorganic ions (e.g., zinc, iron). Coenzymes are organic molecules (e.g., vitamins) that assist enzyme activity.

  • How does substrate concentration affect enzyme activity?

    Increasing substrate concentration increases reaction rate until the enzyme becomes saturated and rate plateaus.

  • What are competitive and noncompetitive enzyme inhibitors?

    Competitive inhibitors bind the active site and can be outcompeted by substrate. Noncompetitive inhibitors bind elsewhere and change enzyme shape.

  • What is allosteric regulation of enzymes?

    Binding of regulatory molecules at sites other than the active site alters enzyme activity, either activating or inhibiting it.

  • Define cooperativity in enzyme regulation.

    Cooperativity is when substrate binding to one active site increases activity at other sites on a multimeric enzyme.

  • What is feedback inhibition?

    End product of a metabolic pathway inhibits an earlier enzyme to prevent overproduction and conserve energy.

  • Why are enzymes often localized in specific cellular compartments?

    Localization restricts enzymatic activity to certain areas, increasing efficiency and regulation.

  • How do cells maintain metabolic disequilibrium?

    Cells are open systems where products of one reaction become substrates for the next, preventing equilibrium and allowing continuous metabolism.