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General Biology: Metabolism and Enzymes

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Termini in questo insieme (23)

  • What is metabolism?

    Metabolism is the sum of all chemical reactions in an organism that transform matter and energy, enabling life processes.

  • What are the three big ideas about metabolism?

    1. Life requires chemical reactions (making/breaking covalent bonds).
    2. Some reactions release energy (exergonic), others store energy (endergonic).
    3. Enzymes lower activation energy to speed reactions.

  • What does the 1st law of thermodynamics state?

    Energy is transferred or transformed but cannot be created or destroyed.

  • Give examples of energy transformation or transfer in a cell.

    Examples include chemical energy in ATP hydrolysis, kinetic energy in molecular movement, and potential energy stored in chemical bonds.

  • Where is energy stored in molecules?

    Energy is stored in the chemical bonds of molecules.

  • What does the 2nd law of thermodynamics state?

    Entropy (disorder) of a closed system increases over time.

  • Is a living organism a closed system? Why is this important?

    No, organisms are open systems exchanging energy and matter with their environment, allowing them to maintain order.

  • Why is some energy considered 'lost' as heat during energy transformations?

    Energy lost as heat increases entropy in the environment; it is not destroyed but dispersed.

  • How do the 1st and 2nd laws of thermodynamics relate to metabolism?

    Organisms transform energy (1st law) and increase entropy in their surroundings (2nd law) while maintaining internal order.

  • What does a negative change in Gibbs free energy (ΔG) indicate?

    A negative ΔG means the reaction is exergonic and occurs spontaneously, releasing energy.

  • What does a positive change in Gibbs free energy (ΔG) indicate?

    A positive ΔG means the reaction is endergonic, requiring energy input to proceed.

  • Define anabolic and catabolic reactions in terms of free energy.

    Anabolic reactions build molecules and are endergonic.
    Catabolic reactions break down molecules and are exergonic.

  • Why are endergonic and exergonic reactions often coupled in metabolism?

    Coupling allows energy released from exergonic reactions to drive endergonic reactions, making processes efficient.

  • What structural feature makes ATP a useful energy source?

    ATP has three phosphate groups with high-energy bonds, especially the bond to the 3rd phosphate, which releases energy when broken.

  • What is the ATP cycle?

    ATP is hydrolyzed to ADP and inorganic phosphate, releasing energy; ADP is then recycled back to ATP using energy from food.

  • How do enzymes affect activation energy?

    Enzymes lower the activation energy needed for reactions, speeding up the reaction without changing ΔG.

  • What is the induced fit model of enzyme action?

    The enzyme changes shape slightly to fit the substrate snugly at the active site, enhancing catalysis.

  • List four mechanisms enzymes use to lower activation energy.

    1. Orienting substrates correctly
    2. Straining substrate bonds
    3. Providing a favorable microenvironment
    4. Covalently bonding to substrate

  • How do temperature and pH affect enzyme activity?

    Extreme temperature or pH can denature enzymes or alter active site shape, reducing activity.

  • What is the difference between competitive and noncompetitive enzyme inhibitors?

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

  • What type of inhibitor was copper when working with catalase?

    Copper acted as a competitive inhibitor for catalase.

  • Why do cells regulate enzyme activity?

    To control metabolic pathways, conserve energy, and respond to environmental changes.

  • Name four modes of enzyme regulation.

    1. Gene regulation
    2. Enzyme activation/deactivation
    3. Feedback inhibition
    4. Localization and compartmentalization