Temperature

• Enzymes


  Catalysts that speed up chemical reactions in living organisms
• Enzymes


  • Have a specific optimum temperature
  • Catalyse a reaction at the maximum rate at their optimum temperature
• Lower temperatures


  Prevent reactions from proceeding or slow them down
• Higher temperatures


  Cause reactions to speed up
• Temperatures continue to increase past a certain point


  The rate at which an enzyme catalyses a reaction drops sharply, as the enzyme begins to denature
• Optimum temperature of an enzyme

  • Varies according to the habitat to which an organism is adapted
• Most enzymes present in living organisms denature at temperatures above 60 °C
• Very few human enzymes can function at temperatures above 50 °C
• Humans maintain a body temperature of about 37 °C and even temperatures exceeding 40 °C can cause the denaturation of some enzymes
• Some bacteria that live in thermal springs have enzymes that can withstand temperatures in excess of 80 °C
• Thermostable enzymes


  Enzymes that can withstand high temperatures
• Temperature coefficient


  The ratio between the rates of a biological reaction at two different temperatures
• For most enzyme-catalysed reactions the rate of the reaction doubles for every 10 °C increase in temperature
• Temperature coefficient (Q)


  Q₁ = 2 for a reaction that follows the pattern of doubling for every 10 °C increase in temperature
• Calculating temperature coefficient


  Temperature coefficient = (rate of reaction at (x+10) °C) / (rate of reaction at x °C)