Metabolism

Cards (76)

  • metabolism
    the totality of an organism's chemical reactions, consisting of catabolic & anabolic pathways, which manage the material & energy resources of an organism
  • Metabolism is a property of life that comes from interactions between molecules
  • metabolic pathway
    a series of chemical reactions that either builds a complex molecule or breaks down a complex molecule into simpler compounds
  • Each pathway is catalyzed by a specific enzyme
  • catabolic pathway
    a metabolic pathway that releases energy by breaking down complex molecules into simpler compounds
  • anabolic pathway
    a metabolic pathway that consumes energy to synthesize a complex molecule from simpler compounds (sometimes called biosynthetic)
  • Catabolic pathway is called "downhill" (releases energy)
  • Anabolic pathway is called "uphill" (stores energy)
  • energy
    the capacity to cause change, especially to do work (move matter against an opposing force)
  • kinetic energy
    the energy associated w/ the relative motion of objects
  • potential energy
    the energy that matter possesses as a result of its location or spatial arrangement (structure)
  • chemical energy
    energy available in molecules for release in a chemical reaction; a form of potential energy
  • thermodynamics
    the study of energy transformations that occur in a collection of matter
  • isolated system
    unable to exchange either energy or matter w/ its surroundings (ex: liquid in a thermos)
  • open system
    energy & matter can be transferred between the system & its surroundings (ex: organisms absorb energy & release heat & metabolic waste products into the surroundings)
  • First Law of Thermodynamics

    the principle of conservation of energy; energy can be transferred & transformed, but it cannot be created or destroyed
  • entropy
    a measure of disorder, or randomness
  • The loss of usable energy during transfer or transformation causes the universe to become more disordered
  • Second Law of Thermodynamics

    the principle stating that every energy transfer or transformation increases the entropy of the universe
  • A spontaneous process can occur without any energy being invested (ex: water flows downhill)
  • A nonspontaneous process cannot occur on its own and it will only happen if energy is added to the system (ex: water will only move uphill if energy is added)
  • For a process to occur spontaneously, it must increase the entropy of the universe
  • free energy
    the portion of a biological system's energy that can perform work when temperature & pressure are uniform throughout the system
  • H\triangle H
    change in system's enthalpy (equivalent to total energy)
  • G=\triangle G=HTS\triangle H-T\triangle S
    change in free energy
  • S\triangle S
    change in system's entropy
  • TT
    absolute temperature in Kelvin (K)
  • G<0\triangle G < 0
    spontaneous
  • G=\triangle G =0 0
    nonspontaneous
  • G>0\triangle G > 0
    nonspontaneous
  • Every spontaneous process decreases the system's free energy
  • The more free energy, the less stable
  • Unstable systems (high G) tend to change so they become stable (lower G)
  • chemical equilibrium
    when chemical reactions get to a point where the forward & backward reactions occur @ the same rate
  • Free energy increases when a reaction is pushed away from equilibrium
  • A system at equilibrium cannot do work because it cannot spontaneously change
  • exergonic reaction

    a spontaneous chemical reaction in which there is a net release of energy
    • negative change in G
    • magnitude of change in G represents the amount of work the reaction can perform
  • endergonic reaction

    a nonspontaneous chemical reaction in which free energy is absorbed from the surroundings
    • positive change in G because this reaction stores free energy
    • change in G is the quantity of energy required to drive the reaction
  • 3 Main Kinds of Work in Cells
    1. Chemical work: the pushing of endergonic reactions
    2. Transport work: pumping substances across membranes
    3. Mechanical work
  • energy coupling
    in cellular metabolism, the use of energy released from an exergonic reaction to drive an endergonic reaction