metabolic pathways

• explain catabolic reactions


  the breakdown of larger molecules to smaller molecules, which relases energy
• explain anabolic reactions

  the build up of smaller molecules to form larger complex molecules, which requires energy
• what can metabolic pathways have?

  reversible steps, irreversibe steps, and alternative routes
• what is a metabolic pathway

  an integrated and controlled pathway of enzyme catalysed reactions within a cell
• what are metabolic pathways controlled by?


  the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes
• what are the two types of reactions that occur within a cell?

  catabolic and anabolic
• what are embedded in membranes

  protein pores, pumps and enzymes
• when does induced fit occur?

  when the active site changes shape to better fit the substrate after it binds
• how does substrate concentration affect enzyme activity?

  the substrate molecules have a high affiity for the active site and the subsequent products have a low affinity, allowing them to leave the active site
• are metabolic pathways reversible?

  some metabolic reactions are reversible and the presence of a substrate or the removal of the product will drive a sequence of reactions in a particular direction
• when does feedback inhibition occur?

  when the end product in the metabolic pathway reaches a critical concentration
• what happens in feedback inhibition?

  the end product inhibits an earlier enzyme, blocking the pathway, and so prevents further synthesis of the end product
• explain competitive inhibition

  competitive inhibitors bind at the active site, preventing the substrate from binding. It can be reversed by increasing substrate concentration
• explain non competitive inhibition

  competitive inhibitors bind away from the active site, but changes the shape of it, which prevens it from binding. They cant be reversed by increasing substrate concentration.