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Chemical Reactions and Energy

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Termini in questo insieme (20)

  • What is energy in biological systems?
    Energy is the capacity to do work or supply heat.
  • What are the two main types of energy?
    Potential energy is stored energy, including chemical bonds. Kinetic energy is energy of motion, including thermal energy.
  • What is enthalpy (H) in the context of chemical bonds?
    Enthalpy is the potential energy stored in chemical bonds.
  • How does electron sharing affect bond potential energy?
    Bonds with electrons shared equally (nonpolar) are longer and weaker with higher potential energy; unequal sharing (polar) results in shorter, stronger bonds with lower potential energy.
  • What is enthalpy change (ΔH) in chemical reactions?
    ΔH represents heat released or absorbed; exothermic reactions release heat, endothermic absorb heat.
  • What is entropy (S)?
    Entropy is the amount of disorder or energy dispersal in a system.
  • What does the First Law of Thermodynamics state?
    Energy cannot be created or destroyed, only transferred or transformed.
  • What does the Second Law of Thermodynamics state?
    Entropy (disorder) of an isolated system always increases.
  • What is an isolated system?
    A system that cannot exchange energy or matter with its surroundings.
  • What determines spontaneity of a chemical reaction?
    Reactions are spontaneous if the change in Gibbs free energy (ΔG) is negative: \(\Delta G = \Delta H - T\Delta S\).
  • What is the hydrophobic effect?
    Hydrophobic molecules cluster in water to reduce ordered water cages, increasing entropy and driving their association.
  • What defines an organic molecule?
    Molecules containing carbon bonded to other elements, often arranged in chains or rings.
  • What are functional groups in organic molecules?
    Specific groups of atoms attached to carbon that determine molecule properties and reactivity.
  • Name six common functional groups attached to carbon atoms.
    Amino, Carboxyl, Carbonyl (aldehydes and ketones), Hydroxyl, Phosphate, Sulfhydryl.
  • What are the four major classes of biological macromolecules?
    Proteins, Nucleic Acids, Carbohydrates, and Lipids.
  • How are biological polymers formed?
    By condensation reactions that link monomers with covalent bonds, releasing water.
  • What is hydrolysis in biological molecules?
    The addition of water to break covalent bonds in polymers, separating monomers.
  • How do lipids differ from other macromolecules in structure?
    Lipids are not polymers linked by covalent bonds but aggregate due to the hydrophobic effect.
  • What happens to entropy during polymerization?
    Entropy decreases because monomers become ordered in a polymer chain.
  • What is phosphorolysis?
    Degradation of polymers by adding phosphate instead of water, producing phosphorylated monomers.