Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about enzymes (GCSE and Key Stage 3)
One of the best ways to help students understand enzyme action is to build Plasticine models of enzymes breaking down (or building up) substrate molecules. Students can modify the models to show denaturation and the effects of temperature, inhibitors and pH. Make sure you stress the different effects of temperature – denaturation versus collision theory. If possible, ask students to film their models and add annotations to help them consider the dynamic nature of enzyme action. Be careful that students don’t attribute properties of organisms to enzymes e.g. heat kills enzymes and make sure students have a good understanding of reaction rates. Spend time exploring some real-life contexts involving enzymes – action of snake venom, death by cyanide and browning of bananas.
The Protein Data Bank provides some beautiful structures of enzymes.
Starting with what enzymes do – they speed things up
The decomposition of hydrogen peroxide is a great place to begin thinking about enzymes. The decomposition of hydrogen peroxide into water and oxygen will happen spontaneously, but the addition of a catalyst e.g. catalase will speed this reaction up. Don’t believe me?! Then have a go at the decomposition of hydrogen peroxide demonstration using MnO2 (a chemical catalyst) and a piece of liver (containing catalase, a biological catalyst). Heat the liver and it no longer works. This will then begin an exploration of denaturation.
Factors that affect enzyme action
GCSE activity for students to apply their knowledge of enzymes. Students work in pairs to apply their understanding of factors that affect enzymes. They will need to consider pH, temperature and enzyme specificity. This activity assesses and consolidates learning by asking students to apply their knowledge to novel situations. (PDF)