Enzymes

What the unit covers

This unit sits in the Molecules and Cells strand of Biology and natural sciences. The resources start with the basics: an enzyme is a protein that acts as a biological catalyst, speeding up a reaction without being used up. Many of the maps describe the active site, where the substrate fits, and the lock and key idea.

Where to start

Begin with the Enzymes mind map that sets out the active site theory. It gives you the vocabulary in one view. Then read the note Enzymes at Work - pH Effects, which explains what pH is and why it matters for enzymes.

Factors and inhibitors

Next, move on to the things that change the rate of reaction:

• Temperature: the rate rises as kinetic energy increases, up to the optimum.
• pH: each enzyme works best in a particular range.
• Concentration: covered in the note Enzymes at Work - Concentration Effects.
• Inhibitors: the mind map 1.9 Enzyme Inhibition separates competitive inhibitors, which bind to the active site, from non-competitive ones, which bind to an allosteric site.

There are also resources on cofactors, poisons and drugs, and immobilising enzymes, for those who want to go further.

Using quizzes and maps together

1. Read a mind map and cover up the branches you can recall.
2. Take the quiz Factors Affecting Enzyme Activity to test the ideas on temperature and collisions.
3. Note the questions you missed and go back to the matching map or note.
4. Use the flashcard decks for short, repeated recall, and the Enzyme practical activity quiz for practical work.

The slide set Required Practical 1 - Enzyme-controlled reactions is useful when you are preparing for the practical side of the topic.

Make it your own

Teachers can set a map or deck for a class, and students can pick a resource that matches their course. Choose one that fits your exam board, then build your own notes around it.