enzymes

• Enzymes increase the rate of reaction by lowering the activation energy of the reaction

  they catalyse.
• Active site is the area of the enzyme where the reaction with the substrate

  takes place.
• Enzymes are specific to substrates they bind to meaning that only one type of

  substrate fits into the active site of the enzyme.
• When the enzyme and substrate form a

  complex, the structure of the enzyme is altered so that the active site of the enzyme fits

  around the substrate. This is called the induced fit model.
• What are the three factors that affect the rate of enzyme-controlled reactions?

  Enzyme concentration

  Substrate concentration

  Temperature
• How does enzyme concentration affect enzyme controlled reactions?

  The rate of reaction increases as enzyme concentration increases as there are more active sites for substrates to bind to, however increasing the enzyme concentration beyond a certain point has no effect on the rate of reaction as there are more active sites than substrates so substrate concentration becomes the

  limiting factor.
• How does substrate concentration affect an enzyme controlled reaction?

  As concentration of substrate increases, rate of reaction increases as more enzyme-substrate complexes are formed. However, beyond a certain point the rate of reaction no longer increases as enzyme concentration becomes the limiting factor.
• How does temperature affect enzyme-controlled reactions?

  The rate of reaction increases up to the optimum temperature, which is the temperature at which enzymes work at their maximum rate. Rate of reaction

  decreases above the optimum temperature.
• describe the lock and key model of enzymes?

  Where the substrate fits into the enzyme in the same way a key fits into a lock, as the substrate and the enzyme have complementary shapes to eachother.
• describe the induced fit model of enzymes?

  Similar to the lock and key model, the enzyme doesnt need to be complementary to the substrate; the substrate will change the active shape of the enzyme so that it fits around the substrate properly.
• How do enzymes work?

  When the enzyme-substrate complex occurs, due to the enzyme mlding around the substrate, strain is put onto the bonds which then lowers the activation energy
• whati s the temperature quotient?

  Q10 is a value for a reaction that shows how much the rate of reaction changes when the temperature is raised by 10 degrees C
• how to work out the temperature quotient?

  Rate at a high temp / rate at a low temp
• what type of protein are enzymes?

  Globular
• What is special about the R groups of enzymes?

  They are hydrophillic to make them soluble in water.
• what is an intracellular enzyme?


  Enzymes which work within cells, e.g. protein synthesis
• what are extracellular enzymes?


  Enzymes which work outside of cells. e.g. pepsin
• what is meant by the fact enzymes are specific>?

  They have an active site which can only combine with specific substrates.