Metabolism

• Metabolism


  All the chemical processes going on continuously inside your body that allow life and normal functioning
• Processes included in metabolism

  • Breaking down nutrients from our food
  • Building and repairing our body
• Metabolic rate


  The amount of energy to maintain life
• An organism must ingest a sufficient amount of food


  To maintain its metabolic rate if the organism is to stay alive for very long
• Catabolism


  Large molecules are broken down into smaller ones releasing energy
• Anabolism


  Small molecules are assembled into larger ones using energy
• Our metabolism is complex but simply has two parts which are carefully regulated by the body to make sure they remain in balance
• Enzymes


  Specific proteins in the body that control the chemical reactions of metabolism
• Thousands of metabolic reactions happen at the same time and are all regulated by the body to keep our cells working and healthy
• Lock and key model

  • An analogy to explain the specific action of an enzyme with a single substrate
• Substrate - molecules which enzymes act on
• • Active site - where the substrate attaches to form an enzyme substrate complex
• Denaturing:

  • The active site is the specific portion of the enzyme that attaches to the substrate
  • The specific shape of the active site must be maintained if the protein is to function properly
  • If the shape of the active site is altered by heat or blocked by poison the enzyme will no longer function and is said to be denatured
• Concentration of reactants (substrate)


  • More substrate = increased rate of reaction
  • More substrate in contact with enzyme
  • Saturation reached when all enzymes are being used
  • Can only increase again if enzyme concentration increases
• Concentration of products


  • Must be continually removed otherwise rate of reaction will slow
  • Build up of products makes it difficult for substrate to make contact with the enzyme
• Temperature


  • Increased temp = increased activity
  • If too high (past optimal temp) it denatures the enzyme
  • Temp too low = decreased activity
• pH


  • Each enzyme has an optimum pH
  • Optimum pH increases activity
• Co-factors


  • Molecules required to activate enzyme
  • Change the shape of the active site so the enzyme can combine with the substrate
  • Ions, non-protein molecules
• Co-enzymes


  • Molecules required to activate enzyme
  • Non-protein organic molecules, vitamins
• Enzyme Inhibitors


  • Substances that slow/stop enzyme activity
  • May be used to control reactions so products are produced in certain amounts
  • Some drugs are enzyme inhibitors
• Digestive enzymes:

  • Amylase is a digestive enzyme that acts on starch in food, breaking it down into smaller carbohydrate molecules
  • Produced in salivary glands and pancreas
  • Protease are enzymes that breaks down protein into amino acids
  • Produced in the stomach and pancreas
  • Lipase is an enzyme that breaks down dietary fats into smaller molecules called fatty acids and glycerol
  • Produced in liver and pancreas