Enzymes 🔐

• What are enzymes?

  They are biological catalysts that speeds up chemical reactions in the body.
• What is the substrate?

  It is the molecule that changes in the reaction.
• What is the active site?


  It is the part where it joins on to its substrate to catalyse the reaction.
• What does substrate- specific mean?

  It means for the enzyme to work, the substrate has to fit into the active site. This is called the 'lock and key' mechanism because the substrate fits into the enzyme just like a key fits into a lock.
• What happens to an enzyme after a reaction?

  Enzymes don't get used up and their shape stays the same after a reaction.
• What is it called when an active site and substrate fit together?


  An enzyme-substrate complex.
• How does temperature affect enzymes?

  The higher the temperature, the more vibrations of particles, more enzyme substrate complexes are formed and more products are produced.
• How does pH affect enzymes?

  The higher the pH towards the optimum pH, the more vibrations of particles so more enzyme- substrate complexes are formed so more products are formed.
• What is the optimum pH that most enzymes have?

  Its often pH 7. For example, pepsin is an enzyme that used to break down proteins in the stomach. It works best at pH 2 which means its well suited to the acidic conditions there
• How does substrate concentration affect enzymes?

  The higher the substrate concentration, the faster the reaction.
• What does optimum mean?

  Optimum means the highest point where the vibrations are the highest and the most enzyme- substrate complexes form so the most products are formed.
• What is the equipment needed for this experiment?

  -spotting tiles

  -a beaker

  -a Bunsen burner

  -a tripod

  -a gauze

  -dropping pipette

  -amylase, starch and buffer solution
• What are the steps of this experiment?

  1.Put drop of iodine solution into every well of a spotting tile.

  2.Place Bunsen burner on a heat-proof mat, a tripod and a gauze over it. Put a beaker of water on top of tripod and heat the water till 35C.

  3.Use a syringe to add 3cm cubed of amylase solution and 1cm cubed of a buffer solution (pH 5) to a boiling tube into beaker of water for 5 mins.

  4. Use a different syringe to add 3cm cubed of a starch solution to the boiling tube.

  5. Mix contents of boiling tube and start a stop clock.
• How do you calculate the rate of reaction?

  Rate= 1000 divided by time
• What are the units for it?


  s to the power of -1.
• How do you investigate the effect of pH on enzyme activity?

  The enzyme amylase catalyzes the breakdown of starch to maltose.It is easy to detect starch using iodine solution - if starch is present, the iodine solution will change from browny-orange to blue-black.