The importance of enzymes is the underlying theme of this topic at A level, in terms of their ability to catalyse a wide range of intracellular and extracellular reactions which can affect the functions from the cellular level to whole organism level. Knowledge of the function of enzymes and the factors which affect their action has led not only to a greater understanding of biological processes, but also to the use of enzymes in a wide range of industrial processes. Students will be required to give examples of enzymes that catalyse intracellular and extra cellular reactions.
It is also a requirement that students not only understand the model of enzyme action, but have an appreciation of how this has changed over time from the lock and key to the induced fit model. Students will need to be able to explain the lowering of activation energy, the need for coenzymes in some enzyme-controlled reactions and the possible mechanisms of enzyme inhibition.
There are a plethora of experiments that can be included within this topic, practical investigations into the effects of PH, temperature, enzyme concentration and substrate concentration on enzyme activities are all possibilities. Students need to be able to confidently interpret graphical data from such experiments.
Whilst this list provides a source of information and ideas for experimental work, it is important to note that recommendations can date very quickly. Do NOT follow suggestions which conflict with current advice from CLEAPSS, SSERC or other recent safety guides. eLibrary users are responsible for ensuring that any activity, including practical work, which they carry out is consistent with current regulations related to Health and Safety and that they carry an appropriate risk assessment. Further information is provided in our Health and Safety guidance.
Links and Resources
This website provides information on enzymes and enzyme action, with links to both metabolic and industrial processes. The animations are colourful, simple and clear. There is also a glossary (key words) which students can refer to, this could be used as the beginning of a glossary for this topic, with students adding all the words that are required at A level as they go through this topic
The level of detail on the website is middle to higher GCSE, but this would work very well as an A level diagnostic starter activity to confirm understanding from GCSE. Students could work in mixed ability pairs and complete each section of this website, answering the questions at the end of each section and also the six question auto marked test.
This short video would make an interesting start to an A level lesson on Enzymes. The video shows how pineapple, when added to a bowl of jelly is able to liquify the jelly, due to the enzyme action in the fruit which breaks down the gelatin in the jelly.
It would be possible to add in extra questions to the video to provide A level challenge, such as why does the pineapple have to be fresh? Why couldn't tinned pineapple be used? What enzyme does the Pineapple contain? When we say the gelatin is being broken down, what do we mean?
Students could quickly carry out this experiment using a) fresh pineapple, b) tinned pineapple and c) another fruit to compare and contrast the results and then write up an A Level standard explanation of what is happening.
This Catalyst article provides a clear summary of the action of enzymes and discusses in some detail the use of enzymes within industrial processes, particularly with reference to the detergent industry.
The article contains a number of prompts for students to complete further research or answer questions. This article would make a suitable homework or self directed study activity towards the beginning of teaching of this topic. Students could read the article, summarise it and complete at least one of the suggested activities. They could then present this at the start of the next lesson.
Alternatively students could use the article as a format for writing and be asked to write a similar style of article on induced fit model of enzyme action or enzyme inhibition.
This problem solving activity from the Royal Society of Chemistry is a group activity to investigate and present findings on the use of catalase in the soap and detergent industry.
This is a good real life application for students to consider and would also support the development of numerical skills.
Students are required to have some background knowledge, although they can also research any required information.
This is one of three practicals listed here from Science & Plants for Schools (SAPS). These materials give a range of suggested activities that investigate enzyme activity in ripening fruit. These include:
• the changes in enzyme activity during ripening and storage
• the activity of the same enzyme in different species
• the loss of an enzyme substrate (such as pectin or starch) during the ripening process
• the appearance of an enzyme product (such as glucose or galactose) during the ripening process
All of these are useful for students to understand the action of enzymes in situ. Small groups of students could be tasked with completing a different assay each and then be prepared to present their methodology, results and interpretation of the results to the rest of the class.
In this investigation from Science & Plants for Schools (SAPS), students look at the effectiveness of enzymes used in the commercial production of fruit juices.
Students are required to complete two practical investigations to consider both the production of the maximum amount of fruit juice and also how enzymes can be reused.
This practical provides a good opportunity for A level students to consider what they are going to do, and why they are doing it, rather than just blindly following a given protocol. The questions provided with this investigation are helpful to set students off thinking about this before they begin the actual practical investigation.
This investigation will help to develop A level students practical skills. There is a detailed protocol to follow, which students will need to read carefully. Students are required to add various reagents and chemicals in precise quantities and there are specific requirements such as keeping the enzyme on crushed ice. Students need to make use of the colorimeter to obtain results.