Enzymes

• What is an enzymes?


  Biological catalyst, that speed up chemical reactions without being used up.

  Lowers activation energy.
• Factors that effect the rate of enzyme action?


  Temperature

  pH concentration

  substrate concentration

  enzyme concentration
• Why is the reduction of activation energy by enzymes important for biological processes?

  It allows reactions to occur at a faster rate under physiological conditions.
• What type of proteins are enzymes?


  Globular
• what do enzymes need to work?


  substrate must bind to the active site

  needs to be complementary
• Describe the lock and key model


  …

  
• describe the induced fit model


  Better model

  
• describe and explain how temperature affects the rate of enzyme action.


  As temperature increases the rate of reaction increases.

  … more kinetic energy, more collisions, more likely for enzyme to bind to substrate.

  The increase in temperature causes the vibration to break some of the bonds.

  active site changes shape, enzyme and substrate no longer complementary.

  enzyme is denatured
• describe and explain how the pH affects the rate of enzyme action


  changing the pH involves changing the concentration of hydrogen and hydroxide ion.

  the change in ion concentration effects the hydrogen and ionic bonds responsible for tertiary structure of enzyme.

  causing a change in active site.

  denatured
• describe and explain the effect of enzyme concentration on enzyme action


  As enzyme concentration increases, the rate of reaction increases.

  More likely to form an enzyme substrate complex.

  But if substrate conc is limited increasing enzyme conc has no further effect.
• describe and explain the effect of substrate concentration on enzyme action.


  increasing the concentration of substrate, increases the rate of reaction.

  … more collisions, so more active sites can be used .

  until saturation point, when all active sites are used up, increasing the conc of substrate has no further effect.

  Initial rate is the fastest rate of reaction.
• What is the independent variable in the investigation of temperature on catalase activity?

  Temperature