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Year 9 iGSCE - Biology

Effects of temperature on enzyme activity

Explain the effects of changes in temperature on enzymes activity in terms off kinetic energy, shape and fit, frequency of effective collisions and denaturing.

The activity of enzymes can be affected by temperature and pH.

Look at the graph to the right, as the temperature increases so does the enzyme’s activity.

This is due to the fact that molecules move faster in heat than cold.

Its important to note, that different enzymes have different ideal temperature and pH.

1. Explain how temperature affects enzyme activity ?

2. What is meant by the term denaturing?

3. How does denaturing affect the active site?

4. Enzyme A’s optimum temperature is 37.5 degrees Celcius, it’s critical temperature is 38    degrees. Draw a graph to demonstrate this.

5. Explain the term, ‘enzyme substrate complex.’

What you’ll notice on the graph is how it drops.

This means the enzyme’s activity has decreased. After 40 degrees the enzymes start dying and their activity eventually stops.

So what happens at 40 degrees?

Every enzyme has an optimum temperature and a critical temperature.

The optimum temperature is the temperature where the enzyme is most active. The critical temperature is the temperature where the enzymes begin to Denature.

You can see on the graph how close the optimum and critical temperature are to each other.

What does Denaturing mean?

First understand that all proteins can be denatured.

By placing a protein in an extreme environment (like temperature), we can break the bonds between it, and change its shape.

When it comes to proteins, and especially enzymes

Structure = Function