The rate of a reaction is the amount of change (e.g. substrate broken down or product made) per unit of time.
Enzyme reaction rate increases as substrate concentration increases until an optimum when all active sites are full.
Enzyme reaction rate increases with temperature due to more collisions, until an optimum when all active sites are full.
Enzyme rate decreases as temperature increases above the optimum as bonds break and the active site becomes denatured.
Interpretation of graphs showing effects of substrate concentration and temperature on enzyme reaction rate.

Common misconception

Enzymes die rather than denature.

The word denature is clearly introduced and a CfU explores the word die vs denature.

Keywords

Rate of reaction - A measure of how much change occurs per unit of time.
Concentration - A measure of the quantity of a dissolved substance in a given volume of solution.
Optimum - The conditions where maximum rate of reaction occurs.
Bond - A force of attraction between atoms in a compound.
Denatured - A permanent change in the shape of an enzyme that stops it from working properly.

Use analogies to explain effects, like a supermarket checkout for substrate concentration, or a loosely folded strip of paper than can be shaken on increased temperature. The practical is really quick to do by pupils themselves, but can also be demonstrated with really cold and really hot potato.

Teacher tip

Equipment

Content guidance

Risk assessment required - equipment

Supervision

Adult supervision required

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

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Starter quiz

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6 Questions

Q1.

What region on an enzyme does the substrate bind to?

substrate site

Correct answer: active site

complex site

enzyme substrate complex site

Q2.

Put the steps in order to show how an enzyme works.

1 - The substrate and enzyme collide.

2 - The substrate binds to the enzyme.

3 - An enzyme substrate complex forms.

4 - A chemical reaction takes place.

5 - The product(s) are released.

6 - The enzyme is free to catalyse another reaction.

Q3.

Enzymes the amount of activation energy needed for a reaction to take place.

Correct Answer: lower, reduce, decrease

Q4.

The shape of the active site is to the substrate.

Correct Answer: complementary, specific

Q5.

Which of the following are enzymes?

lactose

Correct answer: lactase

maltose

Correct answer: maltase

Correct answer: amylase

Q6.

What type of molecule are enzymes?

Correct answer: proteins

lipids

carbohydrates

amino acids

Exit quiz

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6 Questions

Q1.

Which part of an enzyme does the substrate need to collide with for a reaction to take place?

Correct Answer: active site, the active site

Q2.

What is the rate of reaction?

how much substrate has been used up

how much substrate has not been used up

how long it took for the reaction to finish

Correct answer: how much product is formed per unit of time

Q3.

Below are two graphs showing the rates of enzyme facilitated reactions. Match the graph to the factor affecting the rate of reaction.

Correct Answer:temperature,graph B

graph B

Correct Answer:concentration of substance,graph A

graph A

Q4.

Put these steps in order to show what happens as the temperature of an enzyme controlled reaction increases.

1 - As temperature increases, molecules move faster as they have more energy.

2 - The rate of reaction increases, to its optimum.

3 - The bonds holding the enzyme molecules together start to break.

4 - The enzyme's active site changes shape and the substrate no longer fits.

5 - The rate of reaction slows to zero as all the enzyme molecules become denatured.

Q5.

Where on the graph is the substrate concentration greater than the enzyme concentration?

Correct answer: Y

Q6.

Where on the graph could the enzyme concentration be greater than substrate concentration?

Correct answer: A