Chapter 5 - Enzymes Flashcards
What are catalysts?
Catalysts are substances that increase the rate of a chemical reaction without being changed by the reaction.
What are enzymes?
Enzymes are proteins that are involved in all metabolic reactions, where they function as biological catalysts. They are necessary to all living organisms as they maintain reaction speeds of all metabolic reactions at a rate that can sustain life.
How do enzymes act as catalysts during chemical reactions?
Enzymes are specific to one particular substrate as the active site of the enzyme is complementary to the shape of the substrate. This is known as a ‘lock and key’ hypothesis. When the substrate moves into the enzyme’s active site, they become known as an enzyme substrate complex. After the reaction has occurred, the products leave the enzymes active site as they no longer fit it and it is free to take up another substrate.
Describe the process that enzymes use when acting as a catalyst during chemical reactions
- Enzymes and substrates randomly move about in a solution.
- When an enzyme and its complementary substrate collide, with the substrate fitting into the active site of the enzyme, an enzyme-substrate complex forms and the reaction occurs.
- A product, or products, forms from the substrate which is then released from the active site. The enzyme is unchanged and will go on to catalyse further reactions.
How do enzymes become denatured from temperature?
Enzymes work fastest at their optimum temperature (which is around 37 degrees in the human body) but heating to temperature beyond the optimum will break the bonds that hold the enzyme together and it will lose its shape, this is known as denaturation. This means that substrates cannot fit into denatured enzymes as the shape of their active sit has been lost.
How do you increase the activity of enzymes?
Increasing the temperature from 0 degrees to the optimum increases the activity of the enzymes as the more kinetic energy the molecules have, the faster they move and the higher number of effective collisions with the substrate molecules increases leading to a faster rate of reaction.
How do enzymes become denatured from pH?
The optimum pH for enzymes varies as some enzymes are produced in more acidic conditions so they will have a lower optimum pH. If the pH is too high or too low, the bonds that hold the amino acid chains together to make up the protein can be destroyed. This will change the shape of the active site, so the substrate can no longer fit into it and reducing the rate of activity. Moving too far away from the optimum pH will cause the enzymes to be denatured.
