Essential idea: Enzymes control the metabolism of the cell.
Above is just a small part of the IUBMB-Sigma-Nicholson Metabolic Pathways Chart aims to show all the metabolic pathways found in eukaryote cells. The chart in it's entirety shows how complex the chemicals reactions needed to support life in a single cell unit. This was mentioned earlier in 2.1, but in addition to the complexity now add to that idead the fact that every arrow on the chart shows an enzyme controlling the conversion of compounds.
Understandings, applications and skills:
| 2.5.U1 | Enzymes have an active site to which specific substrates bind. |
| 2.5.U2 | Enzyme catalysis involves molecular motion and the collision of substrates with the active site. |
| 2.5.U3 | Temperature, pH and substrate concentration affect the rate of activity of enzymes. [Students should be able to sketch graphs to show the expected effects of temperature, pH and substrate concentration on the activity of enzymes. They should be able to explain the patterns or trends apparent in these graphs.] |
| 2.5.U4 | Enzymes can be denatured. |
| 2.5.U5 | Immobilized enzymes are widely used in industry. |
| 2.5.A1 | Methods of production of lactose-free milk and its advantages. [Lactase can be immobilized in alginate beads and experiments can then be carried out in which the lactose in milk is hydrolysed.] |
| 2.5.S1 | Design of experiments to test the effect of temperature, pH and substrate concentration on the activity of enzymes. |
| 2.5.S2 | Experimental investigation of a factor affecting enzyme activity. (Practical 3) |
[Text in square brackets indicates guidance notes]
Starter
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What is lactose intolerance and how has it come about? How does lactose link to other elements of the course? Watch the HHMI video 'Got lactase?' and discuss.
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A fun musical introduction by Mr W.
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Presentation and notes
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The presentation is designed to help your understanding. The notes outline is intended to be used as a framework for the development of student notes to aid revision.
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Below are the notes for this topic. Alternatively the 2.5 Enzymes bottom line template can be used as a note construction template in itself or as a checklist if you are using your own or another template such as the Cornell style template.
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Weblinks
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Enzymes - what are they and how do they work
What is an enzyme? is a great place to start by Northland Community College How enzymes work by Biotopics How enzymes work by McGraw and Hill Activation energy and the stressing of bonds explained by St Olaf College Enzyme action and the hydrolysis of sucrose by McGraw and Hill Specificity Conformational change (aka the induced fit model) by St Olaf College Kinetics Enzyme Kinetics is a simulation which shows how different factors affect enzyme activity by KScience Enzyme kinetics from Wiley Interscience |
Denaturation
Denaturation process by Biotopics Inhibition and Metabolic Pathways Allosteric (non-competitive) inhibition by St Olaf College Example of a biochemical pathway by St Olaf College Feedback (end product) inhibition from McGraw Hill Example metabolic pathway, from McGraw Hill Enzyme inhibition from Wiley Interscience |
Nature of science:
Experimental design—accurate, quantitative measurements in enzyme experiments require replicates to ensure reliability. (3.2) [should be discussed and covered by 2.5.S1 and 2.5.S2]
Theory of knowledge:
Development of some techniques benefits particular human populations more than others. For example, the development of lactose-free milk available in Europe and North America would have greater benefit in Africa/Asia where lactose intolerance is more prevalent. The development of techniques requires financial investment. Should knowledge be shared when techniques developed in one part of the world are more applicable in another?
