Rate of Reaction
Biology: AQA GCSE Higher, topic 2.2.3
Factors Affecting the Rate of Enzyme Action
The factors that affect the rate (speed) of enzyme action are:
Temperature
- Increasing the temperature of a working enzyme initially increases the reacting activity.
- Enzymes have an optimum temperature. Once this temperature is reached, the activity decreases.
- Past a certain temperature, the active site changes shape, and the enzyme is denatured (loses its catalytic activity).
pH (measure of acidity)
- Enzymes have an optimum pH (measure of acidity).
- If the pH changes away from the optimum pH, the enzyme activity decreases.
- If the pH is too low or too high, the enzyme is denatured and will not function.
Test yourself on Rate of Reaction
What happens to an enzyme if the pH moves far past its optimum, becoming too high or too low?
What happens to an enzyme's activity when a working enzyme is first heated, before its temperature reaches the optimum?
A working enzyme is gradually heated from a low temperature to a temperature far above its optimum. What happens to its activity over this whole range?
An enzyme's activity starts to decrease once the temperature rises above its optimum. According to the source, what happens next as the temperature keeps rising?
What is similar about how extreme temperature and extreme pH affect an enzyme, according to the source?