General

• Biological catalysts


  • speed up the rate of reaction
  • are not used up or undergo permanent change during processes
  • function in living systems
  • control metabolic pathways
• Globular proteins

  • complex tertiary or quaternary structures
  • water soluble
• Enzymes

  • produced inside cells via protein synthesis
  • some remain inside cells
  • some are secreted to work outside cells
• Extracellular


  Work outside of the cell - e.g. digestive enzymes in the gut
• Intracellular


  work inside the cell
• Extracellular digestion

  • hyphae of fungi secrete enzymes directly onto their food
  • can absorb smaller, simple molecules through hyphae
• Catalase - intracellular


  • converts hydrogen peroxide into water and oxygen
  • hydrogen peroxide is a by-product of many metabolic reactions, it is harmful to cells and tissue
• Amylase - extracellular


  • hydrolyses starch into simple sugars (maltose)
  • secreted by salivary glands for the mouth and the pancreas for the small intestine
• Trypsin - extracellular


  • secreted by the pancreas for the small intestine
  • breaks proteins down into peptides and amino acids
• Extracellular enzymes in digestion


  • macromolecules are too large to enter cells
  • enzymes break them down so they become simple molecules that cells can absorb