3.2 - Factors That Affect Enzyme Action Flashcards
Describe how temperature effects the rate of enzyme-catalysed reactions
Like with any reaction, a higher temperature increases the rate at first. The enzymes and substrate have more energy, so they move about more and are more likely to collide and form enzyme-substrate complexes. But if it gets too hot, some of the bonds holding the enzymes together break. This changes the shape of the enzyme’s active site, so the substrate won’t fit any more. The enzyme is said to be denatured. All enzymes have an optimum temperature that they work best at.
Describe how pH effects the rate of enzyme-catalysed reactions
If it’s too high or too low, the pH interferes with the bonds holding the enzyme together. This changes the shape of the active site and denatures the enzyme. All enzymes have an optimum pH that they work best at. It’s often neutral pH 7, but not always.
Describe how substrate concentration affects the rate of enzyme-catalysed reactions
Substrate concentration also affects the rate of reaction - the higher the substrate concentration, the faster the reaction. This is because it’s more likely that the enzyme will meet up and react with a substrate molecule. This is only try up to a point though. After that, there are so many substrate molecules that the enzymes have about as much as they can cope with (all the active sites are full), and adding more makes no difference.
Describe how substrate concentration affects the rate of enzyme-catalysed reactions
Substrate concentration also affects the rate of reaction - the higher the substrate concentration, the faster the reaction. This is because it’s more likely that the enzyme will meet up and react with a substrate molecule. This is only true up to a point though. After that, there are so many substrate molecules that the enzymes have about as much as they can cope with (all the active sites are full), and adding more makes no difference.
Explain how increasing the temperature can cause an enzyme to denature
High temperatures start to break the bonds holding the enzyme together. This causes the enzyme and it’s active site to change shape. This means the enzymes active site will no longer be complementary to the substrate.
