1.4 1

• Enzymes


  Globular proteins that catalyse a wide range of intracellular reactions as well as extracellular
• Enzymes


  • They are biological catalysts that control the rate of reactions in cells and organisms
  • They speed up chemical reactions in cells without changing the conditions in the cytoplasm
• Catalyst


  A substance that changes the rate of a reaction without changing the substances produced. The catalyst is unaffected at the end of the reaction and can be used again.
• Enzyme


  A biological catalyst that controls the rate of the reactions that take place in individual cells and in whole organisms
• Specificity


  The characteristic of enzymes that means each enzyme will only catalyse a specific reaction or group of reactions
• Changes in temperature and pH affect the efficiency of an enzyme because they affect the intramolecular bonds within the protein that are responsible for the shape of the molecule.
• Anabolic reactions


  Reactions that build up (synthesise) new molecules in a cell
• Catabolic reactions


  Reactions which break down substances within a cell
• Metabolism


  The sum of the anabolic and catabolic processes in a cell
• Metabolic chain (metabolic pathway)


  A series of linked reactions in the metabolism of a cell
• Intracellular enzymes


  Enzymes that catalyse reactions within a cell
• Extracellular enzymes


  Enzymes that catalyse reactions outside of the cell in which they were made
• Most enzymes have several names including a relatively short recommended name, a longer systematic name describing the type of reaction being catalysed, and a classification number.
• The names of most enzymes give you useful information about the role of the enzyme in the cell or the body.
• James B. Sumner extracted the first pure, crystalline enzyme from jack beans - urease, the enzyme that catalyses the breakdown of urea

  1926