AQA A LEVEL BIOLOGY复习笔记1.4.1 Many Proteins are Enzymes

• Enzymes are biological catalysts
  • ‘Biological’ because they function in living systems
  • ‘Catalysts’ because they speed up the rate of chemical reactions without being used up or changed

   

• Enzymes are also globular proteins
• Critical to the enzyme's function is the active site where the substrate binds
• Metabolic pathways are controlled by enzymes in a biochemical cascade of reactions
  • Virtually every metabolic reaction within living organisms is catalysed by an enzyme – enzymes are therefore essential for life to exist

   

• Enzymes can be intracellular or extracellular referring to whether they are active inside or outside the cell respectively
• Intracellular enzymes are produced and function inside the cell
• Extracellular enzymes are secreted by cells and catalyse reactions outside cells (eg. digestive enzymes in the gut)

Enzymes Table