Metabolic pathways

    Cards (20)

    • Metabolic Pathways
      Integrated and controlled pathways of enzyme-catalysed reactions within a cell
    • Metabolic Pathways
      • Can have reversible steps
      • Can have irreversible steps
      • Can have alternative routes
    • Anabolic Reactions

      Build up large molecules from small molecules and require energy
    • Catabolic Reactions

      Break down large molecules into smaller molecules and release energy
    • Membranes
      • Consist of proteins and phospholipids
      • Phospholipids create a bilayer and are constantly moving, giving the membrane flexibility
    • Channel-forming proteins

      Create pores which control the diffusion of small molecules across the cell
    • Diffusion
      Movement of molecules from an area of high concentration to an area of low concentration
    • Active transport
      Movement of molecules from an area of low concentration to an area of high concentration and requires energy in the form of ATP
    • Sodium-Potassium pump

      An example of a carrier protein involved in active transport
    • ATP Synthase
      An example of a membrane embedded enzyme which produces ATP from ADP + Pi
    • Activation Energy
      The energy required to initiate a chemical reaction
    • Enzymes
      Lower the activation energy required for a reaction to take place
    • Affinity
      • The activity of enzymes depends on their flexible and dynamic shape
      • Substrate molecules have high affinity for the active site of an enzyme (bind readily)
      • Products of enzyme reactions have a low affinity for the active site of an enzyme, allowing them to leave the active site
    • Induced Fit
      The enzyme is flexible and the substrate can induce the active site to change shape to better fit the substrate after the substrate binds
    • Direction of enzyme-controlled reactions
      1. Presence of a substrate or removal of a product will drive a sequence of reactions in a particular direction
      2. Most enzymes can also work in reverse
    • As the concentration of Substrate or Enzyme increases
      The rate of an enzyme-controlled reaction increases
    • If either enzyme or substrate concentration is limited
      The rate reaction will only increase up to a point, beyond which the rate of reaction remains constant
    • Competitive Inhibitors
      • Bind at the active site of the enzyme, preventing the substrate from binding
      • Competitive inhibition can be reversed by increasing substrate concentration
    • Non-competitive Inhibitors

      • Bind away from the active site (at an allosteric site) but change the shape of the active site, preventing the substrate from binding
      • Non-competitive inhibition cannot be reversed by increasing substrate concentration
    • Feedback Inhibition
      The end-product in the metabolic pathway reaches a critical concentration and then inhibits an earlier enzyme, blocking the pathway and preventing further synthesis of the end-product
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