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Bio Chemistry: Cellular Energy and Metabolism

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Terms in this set (42)

  • Where does the body obtain energy?
    From the oxidation of food molecules.
  • Where does most energy generation occur in eukaryotic cells?
    In the mitochondria.
  • What is an exergonic reaction?
    A favorable reaction that releases free energy and can occur spontaneously.
  • What is an endergonic reaction?
    An unfavorable reaction that requires an input of free energy.
  • What is metabolism?
    The sum of all chemical reactions in an organism.
  • What is catabolism?
    The breakdown of molecules, generally releasing energy.
  • What is anabolism?
    The building of larger molecules from smaller ones, generally requiring energy.
  • What is a metabolic pathway?
    A series of connected chemical reactions where the product of one reaction becomes the substrate for the next.
  • What is the cytosol?
    The fluid inside a cell in which organelles are suspended.
  • What is the mitochondrial matrix?
    The innermost compartment of a mitochondrion, where the citric acid cycle occurs.
  • What happens in the first stage of food catabolism?
    Food is digested into smaller molecules that can be absorbed into cells.
  • What happens in the second stage of food catabolism?
    Carbohydrates, lipids, and proteins are broken down through pathways that produce acetyl-CoA.
  • What is acetyl-CoA?
    Acetyl coenzyme A; a molecule that carries a two-carbon acetyl group into the citric acid cycle.
  • What happens in the third stage of food catabolism?
    Acetyl groups are oxidized in the citric acid cycle, producing reduced coenzymes and releasing carbon dioxide.
  • What happens in the fourth stage of food catabolism?
    Electrons from reduced coenzymes pass through the electron-transport chain, supporting ATP production.
  • What is ATP?
    Adenosine triphosphate; the cell’s principal energy-transfer molecule.
  • How is ATP formed from ADP?
    A phosphate group is added to ADP using energy, forming ATP.
  • How does ATP help power cellular work?
    ATP hydrolysis releases energy that can be coupled to energy-requiring processes.
  • What is a coupled reaction?
    A process in which an energy-releasing reaction drives an energy-requiring reaction.
  • Why are endergonic reactions coupled to exergonic reactions?
    The energy released by the exergonic reaction makes the combined process favorable.
  • What is oxidation?
    The loss of electrons.
  • What is reduction?
    The gain of electrons.
  • What is a coenzyme?
    A molecule that assists an enzyme in carrying out a reaction.
  • How do redox coenzymes function in metabolism?
    They cycle between oxidized and reduced forms, carrying electrons between reactions.
  • What happens when NAD+ is reduced?
    It gains electrons and a hydrogen ion to form NADH.
  • What happens when FAD is reduced?
    It gains electrons and hydrogen to form FADH2.
  • What is the citric acid cycle?
    A cyclic pathway that oxidizes acetyl groups and produces reduced coenzymes, carbon dioxide, and GTP.
  • How many reactions are in the citric acid cycle?
    Eight.
  • Why is the citric acid cycle considered cyclic?
    The final reactions regenerate oxaloacetate, which is needed to begin another turn.
  • What combines with the acetyl group at the start of the citric acid cycle?
    Oxaloacetate combines with the acetyl group to form citrate.
  • How many carbon dioxide molecules are released per acetyl group oxidized in the citric acid cycle?
    Two.
  • What are the reduced coenzymes produced per turn of the citric acid cycle?
    Three NADH and one FADH2.
  • How much GTP is produced per turn of the citric acid cycle?
    One GTP, which can be used to make ATP.
  • What is the electron-transport chain?
    A series of protein complexes that transfer electrons and help create a hydrogen-ion gradient.
  • Where is the electron-transport chain located in eukaryotic cells?
    In the inner mitochondrial membrane.
  • What delivers high-energy electrons to the electron-transport chain?
    Reduced coenzymes, including NADH and FADH2.
  • What is coenzyme Q?
    A mobile electron carrier that transfers electrons within the electron-transport chain.
  • How does electron transport help build a hydrogen-ion gradient?
    Energy released as electrons move through the chain is used to pump hydrogen ions across the inner mitochondrial membrane.
  • What is oxidative phosphorylation?
    The production of ATP using the hydrogen-ion gradient generated by electron transport.
  • What is ATP synthase?
    An enzyme that uses the flow of hydrogen ions to produce ATP from ADP and phosphate.
  • How are electron transport and ATP synthesis coupled?
    Electron transport builds a hydrogen-ion gradient, and ATP synthase uses that gradient to make ATP.
  • What is the final electron acceptor in the electron-transport chain?
    Oxygen; it accepts electrons and hydrogen ions to form water.