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Energy and Enzymes: An Introduction to Metabolism

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Termini in questo insieme (24)

  • What is energy in biological terms?
    Energy is the ability to perform work, which in biology is a transfer of energy causing an overall change.
  • Define potential and kinetic energy with examples.
    Potential energy is stored energy available to do work (e.g., glucose molecule). Kinetic energy is energy of motion (e.g., water rushing over a waterfall).
  • What is a biological system in thermodynamics?
    A system is the specific portion of matter studied, while surroundings are everything else. Biological systems transfer both energy and matter with surroundings.
  • State the First Law of Thermodynamics.
    Energy cannot be created or destroyed, only transferred or transformed. The total energy in the universe remains constant.
  • What does entropy measure?
    Entropy measures disorder or randomness; higher disorder means higher entropy. Natural reactions tend to increase universal entropy.
  • Explain the Second Law of Thermodynamics in biological context.
    No energy transfer is 100% efficient; some energy is lost as heat, increasing the entropy of the universe.
  • What are reactants and products in a chemical reaction?
    Reactants are starting materials, and products are the resulting materials after bonds are made or broken.
  • Differentiate between endergonic and exergonic reactions.
    Endergonic reactions require energy input (energy enters), while exergonic reactions release energy (energy exits).
  • What is ATP and its role in cells?
    Adenosine Triphosphate (ATP) is a high-energy molecule that powers cellular activities by hydrolyzing phosphate bonds to release energy.
  • Describe ATP hydrolysis.
    Breaking bonds between phosphate groups in ATP releases energy and forms ADP; sometimes ADP can be further hydrolyzed to AMP.
  • What is energy coupling in metabolism?
    Energy released by exergonic reactions (like ATP hydrolysis) is used to drive endergonic reactions, providing necessary energy input.
  • Define phosphorylation and its effects.
    Phosphorylation is the transfer of a phosphate group from ATP to another molecule, which can activate the molecule or change protein shape.
  • What is an enzyme and its function?
    An enzyme is a catalyst that speeds up chemical reactions without being consumed, by lowering activation energy.
  • List some functions of enzymes in cells.
    Enzymes build molecules, copy DNA, and break down food molecules.
  • Name environmental factors affecting enzyme activity.
    Temperature, pH, and substrate concentration affect enzyme activity; extreme conditions can denature enzymes and reduce activity.
  • What is activation energy (EA)?
    Activation energy is the minimum energy required to start a chemical reaction by reaching the transition state.
  • How do enzymes affect activation energy?
    Enzymes lower the activation energy barrier, allowing reactions to proceed faster.
  • Describe the enzyme-substrate complex.
    A substrate binds to an enzyme's active site forming the enzyme-substrate complex; after catalysis, products are released and enzyme remains unchanged.
  • What are cofactors and coenzymes?
    Cofactors are non-protein helpers (e.g., metal ions) required for enzyme activity; coenzymes are organic cofactors derived from vitamins.
  • Explain competitive and noncompetitive enzyme inhibition.
    Competitive inhibitors bind the active site competing with substrate; noncompetitive inhibitors bind allosteric sites, changing enzyme shape and activity.
  • What is metabolism and metabolic pathways?
    Metabolism is the sum of all chemical reactions in an organism; metabolic pathways are series of reactions modifying substrates stepwise.
  • Differentiate catabolic and anabolic pathways.
    Catabolic pathways break down molecules releasing energy; anabolic pathways build larger molecules consuming energy.
  • What is negative feedback in metabolism?
    Negative feedback occurs when the final product inhibits an earlier step, regulating the pathway like a 'red light.'
  • What is positive feedback in metabolism?
    Positive feedback occurs when the final product stimulates an earlier step, enhancing the pathway like a 'green light.'