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Seren is attempting to get into her house but is having some difficulty as her key won’t fit in the lock. In anger, she questions what is wrong with her lock and key. Alfred, the science app, responds by explaining how enzymes work in relation to the ‘lock and key’ model. Alfred explains that enzymes are proteins with specific shapes that can bind with substrates through their specific active site. Alfred also explains how temperature and pH can affect the enzyme’s ability to bind with the substrate.

This clip could be used to introduce the topic and review the KS3 knowledge and understanding of enzymes. The students could be led into conducting a series of investigations into the effect of pH and temperature on optimal enzyme activity. The findings could be used to explore the efficiency of using enzymes in industry to speed up reactions and the use of enzymes in biological washing powders and energy efficiency in the home. More able and talented students could explore the structure of the molecule and the synthesis of proteins, linking to the effect on a person if there is a fault in their coding that may lead to a mutation of the enzyme and the subsequent consequences to health.