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Energy and Cellular Metabolism - Anatomy & Physiology Ch4.

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Terms in this set (24)

  • What is energy in biological systems?
    Energy is the capacity to do work, including chemical work (making/breaking bonds), transport work (moving molecules), and mechanical work (movement or shape change).
  • Distinguish between kinetic and potential energy.
    Kinetic energy is energy of motion (thermal, radiant, electrical), while potential energy is stored energy (chemical, mechanical, nuclear).
  • State the first law of thermodynamics.
    Energy in the universe is constant; it can neither be created nor destroyed. The human body is an open system exchanging energy.
  • State the second law of thermodynamics.
    Processes proceed in a direction that spreads out energy, such as breaking large molecules into smaller ones or diffusion from high to low concentration.
  • What is free energy in chemical reactions?
    Free energy is the potential energy stored in chemical bonds available to do work during reactions.
  • Define exergonic reactions.
    Reactions where free energy of reactants is greater than products, releasing energy and proceeding spontaneously. Example: catabolic reactions.
  • Define endergonic reactions.
    Reactions where free energy of reactants is less than products, requiring energy input and not proceeding spontaneously. Example: anabolic reactions.
  • What is activation energy?
    The energy barrier that must be overcome for reactants to reach the transition state and form products, limiting reaction speed.
  • How do enzymes affect activation energy?
    Enzymes lower the activation energy, speeding up chemical reactions without being consumed.
  • Name the four major categories of enzymatic reactions.
    1. Redox reactions 2. Hydrolysis-dehydration reactions 3. Addition-subtraction-exchange reactions 4. Ligation reactions.
  • Explain oxidation and reduction in redox reactions.
    Oxidation is loss of electrons; reduction is gain of electrons. They always occur together in redox reactions.
  • What is hydrolysis and condensation?
    Hydrolysis breaks bonds using water; condensation (dehydration) forms bonds releasing water.
  • Describe allosteric regulation of enzymes.
    A modulator binds to the enzyme's regulatory site, changing its shape and activity, which can increase or decrease enzyme function.
  • Describe covalent regulation of enzymes.
    Enzyme activity is altered by forming or breaking covalent bonds (commonly phosphate groups) with the enzyme, switching it between active and inactive states.
  • What is feedback inhibition in metabolism?
    The end product of a pathway inhibits an earlier step, preventing overproduction and regulating the pathway.
  • Define metabolism and distinguish catabolic from anabolic reactions.
    Metabolism is the sum of all chemical reactions in cells. Catabolic reactions break down molecules; anabolic reactions build molecules.
  • List five ways cells control metabolic pathways.
    1. Control enzyme concentrations 2. Produce modulators 3. Use different enzymes for reversible reactions 4. Compartmentalize enzymes 5. Maintain ATP/ADP ratio.
  • Outline the stages of aerobic glucose metabolism.
    1. Glycolysis 2. Linking step (pyruvate to Acetyl CoA) 3. Krebs cycle 4. Oxidative phosphorylation (electron transport chain).
  • What happens during glycolysis?
    Glucose (6C) splits into two pyruvate (3C), producing 2 ATP (net) and 2 NADH in the cytosol.
  • What is the role of the Krebs cycle?
    Acetyl CoA is converted to citrate and broken down, releasing energy to reduce coenzymes NAD+ and FAD to NADH and FADH2.
  • Describe the electron transport chain (ETC).
    ETC uses electrons from NADH and FADH2 to pump H+ across the mitochondrial membrane, creating an electrochemical gradient.
  • What is chemiosmosis and ATP synthase function?
    H+ flows back through ATP synthase, which uses this energy to phosphorylate ADP to ATP.
  • How does anaerobic metabolism produce ATP?
    With low oxygen, glycolysis continues by converting pyruvate to lactate, producing 2 ATP per glucose.
  • What is the efficiency of glucose oxidation to ATP?
    About 38.8% of energy from glucose oxidation is captured in ATP; the rest is lost as heat.