Enzymes (B) Flashcards
What is the effect of substrate concentration on the rate of enzyme activity and why?
Increasing the substrate concentration will increase the rate of reaction. This is because the rate of reaction initially increases as collisions between substrate and enzyme molecules are more likely to occur. Then the rate of reaction levels out as the active sites of all the enzyme molecules are taken up by substrate molecules
What happens at low, medium and high substrate concentrations?
Low: too few substrate molecules to occupy all the available active sites
Medium: all active sites are occupied at one time
High: the addition of further substrate molecules has no effect as all active sites are already occupied at one time
What is the effect of enzyme concentration on the rate of enzyme activity and why?
When the concentration of substrate is in excess, then an increase in enzyme concentration increases the rate of reaction. This is because when there are more enzyme molecules there are more active sites available. This increases the number of collisions between active sites and substrates to form more enzyme-substrate complexes
What is the effect of temperature on enzyme reaction and why?
As the temperature increases the rate of reaction increases up to the optimum temperature. This is because an increase in temperature provides the molecules with more kinetic energy resulting in more collisions between the active site of enzymes and substrate molecules and therefore more enzyme-substrate complexes are formed
What happens at lower temperatures to the rate of reaction?
The rate of reaction is slowed down by the reduced kinetic energy of the reactant molecule
What is the optimum temperature for enzyme activity?
The temperature where the rate of reaction is at a maximum
What happens to the rate of reaction beyond the optimum temperature?
Due to the substrate having difficulty binding to the altered active site. The active site has changed shape and is no longer complementary, so less enzyme-substrate complexes form
What is the average temperature of denaturation of proteins?
50 C
What happens to the enzyme beyond the optimum temperature?
The tertiary structure denatures as hydrogen and ionic bonds break, altering the active site and reducing its ability to bind to substrates, leading to a loss of function
What is the effect of pH on the rate of reaction for enzymes?
Enzymes are only active over a narrow pH range
What happens with very different pHs from the optimum to the enzyme?
At lower or higher pHs than the optimum, denaturation occurs
