Your task is to watch the following video and make a mind map with the info it contains. With the help of your mind map, you will share the info with the class.

And what about temperature and enzymes?



Things to remember:

  • Enzymes are proteins that work as biological catalysts.
  • Enzymes are named according to the substrate on which they act. Proteases act on proteins, carbohydrases on carbohydrates and lipaseson fats (lipids). The substance that is produced by the reaction is called the product.
  • An enzyme molecule has a depression called its active site, which is exactly the right shape for the substrate to fit into. The enzyme can be thought of as a lock, and the substrate as the key.
  • Reactions catalysed by enzymes work faster at higher temperatures, up to an optimumthat differs for different enzymes. Above the optimum temperature, reaction rate rapidlydecreases.
  • At low temperatures, molecules have low kinetic energy, so collisions between enzymeand substrate molecules are infrequent. As temperature rises they collide more frequently,increasing reaction rate.
  • Above the optimum temperature, the vibrations within the enzyme molecule are so great that it begins to lose its shape. The enzyme is said to be denatured. The substrateno longer fits into the active site and the reaction stops.
  • Reactions catalysed by enzymes work fastest at a particular pH. The optimum pH for mostenzymes is around pH7 (neutral), but some have an optimum pH much higher or lowerthan this.
  • Extremes of pH cause enzyme molecules to lose their shape, so they no longer bind withtheir substrate.
  • Amylase is found in seeds. When the seed begins to germinate, the amylase is activated and catalyses the breakdown of insoluble starch to soluble maltose in the seed. Themaltose is used by the growing embryo as an energy source and to make cellulose for new cell walls.
  • Biological washing powders contain enzymes, often obtained from microorganismssuch as bacteria or fungi. The enzymes break down proteins or fats on the fabric, forming watersoluble substances that can be washed away.
  • Pectinase is used to break down cell walls in fruits, making it easier to extract juice from them.
  • The antibiotic penicillin is made by cultivating the fungus Penicillium in a fermenter. Thefermenter is kept at the correct pH and temperature for the enzymes of the fungus to work well.

Now, see how much you have learned.




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