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Physiology Ch. 3 Exam review

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Termini in questo insieme (30)

  • What are reactants and products in a chemical reaction?
    Reactants are substances on the left side of the equation that are transformed into products, which are on the right side.
  • Define metabolism.
    Metabolism is the sum of all chemical reactions inside cells, including catabolic (breakdown) and anabolic (building) reactions.
  • Difference between catabolic and anabolic reactions.
    Catabolic reactions break down molecules and release energy (ΔG negative). Anabolic reactions build molecules and require energy (ΔG positive).
  • What happens in hydrolysis and condensation reactions?
    Hydrolysis adds water to break covalent bonds (catabolic). Condensation removes water to form covalent bonds (anabolic).
  • Explain phosphorylation and dephosphorylation.
    Phosphorylation adds a phosphate group to a molecule, often catalyzed by kinases. Dephosphorylation removes it, catalyzed by phosphatases.
  • What is an oxidation-reduction (redox) reaction?
    Oxidation is loss of electrons or hydrogen atoms; reduction is gain of electrons or hydrogen atoms. They always occur together.
  • State the first law of thermodynamics.
    Energy can be transformed from one form to another but cannot be created or destroyed.
  • State the second law of thermodynamics.
    Natural processes increase disorder; some energy is lost as heat and is unusable for work.
  • What are the three types of work performed by cells?
    Chemical work (anabolic reactions), transport work (active transport), and mechanical work (muscle contraction, cilia movement).
  • Describe coupled reactions involving ATP.
    Energy from exergonic catabolic reactions is stored in ATP, which then drives endergonic anabolic reactions.
  • What is chemical equilibrium in reactions?
    When forward and reverse reaction rates are equal, ΔG = 0, no net work is done, and the cell tries to avoid this state.
  • Explain the law of mass action.
    Increasing reactant concentration pushes reactions forward; increasing product concentration pushes reactions backward.
  • What limits the speed of a chemical reaction?
    The activation energy barrier limits reaction speed; higher activation energy means slower reaction.
  • How do enzymes affect activation energy?
    Enzymes lower the activation energy, speeding up the reaction without being consumed.
  • What is substrate specificity of enzymes?
    Enzymes bind only specific substrates due to the shape of their active site.
  • Describe the induced fit model of enzyme action.
    The enzyme changes shape slightly to fit the substrate, straining bonds and lowering activation energy.
  • What roles do cofactors and coenzymes play in enzyme function?
    Cofactors are inorganic ions stabilizing the active site; coenzymes are organic molecules that transfer chemical groups or electrons.
  • How does substrate concentration affect enzyme activity?
    Increasing substrate concentration increases reaction rate until enzymes become saturated.
  • What happens to enzyme activity at temperatures above optimal?
    Enzymes denature, active site shape changes, and reaction rate decreases.
  • What is allosteric regulation of enzymes?
    Modulators bind to a site other than the active site, changing enzyme shape and activity; inhibitors decrease and activators increase activity.
  • Explain feedback inhibition in metabolic pathways.
    An intermediate or end-product inhibits an earlier enzyme in the pathway, slowing product formation.
  • What is glycolysis and where does it occur?
    Glycolysis is the breakdown of glucose into two pyruvate molecules, producing ATP and NADH; it occurs in the cytosol.
  • What happens during formation of acetyl CoA?
    Pyruvate is converted to acetyl CoA in the mitochondrial matrix, producing NADH and releasing CO2.
  • Outline the citric acid (Kreb’s) cycle products.
    Each glucose yields 6 NADH, 2 FADH2, 2 ATP, and 4 CO2 through the cycle in the mitochondrial matrix.
  • Describe the electron transport chain (ETC) and oxidative phosphorylation.
    ETC transfers electrons from NADH/FADH2 to oxygen, pumping H+ to create a gradient used by ATP synthase to make ATP.
  • What is chemiosmosis?
    The flow of protons down their concentration gradient through ATP synthase, driving ATP production.
  • Why do cells perform fermentation?
    When oxygen is absent or mitochondria are overwhelmed, fermentation regenerates NAD+ by converting pyruvate to lactate or ethanol.
  • Define glycogenesis, glycogenolysis, and gluconeogenesis.
    Glycogenesis: glycogen synthesis; glycogenolysis: glycogen breakdown; gluconeogenesis: new glucose production from non-carbohydrates.
  • What is lipolysis and lipogenesis?
    Lipolysis is the breakdown of lipids for energy; lipogenesis is the synthesis of lipids for storage.
  • What is proteolysis and why is it harmful as an energy source?
    Proteolysis is protein breakdown; using proteins for energy produces ammonia, which can harm liver and kidneys.