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Enzymes. Objectives. At the end of today’s lesson, we should be able to: define what are catalysts define what are enzymes state uses of enzymes. Catalyst. So what are catalyst?
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Objectives • At the end of today’s lesson, we should be able to: • define what are catalysts • define what are enzymes • state uses of enzymes
Catalyst • So what are catalyst? • A catalyst is a substance which can alter a chemical reaction, without itself being chemically changed at end of reaction.
Catalyst • Inorganic catalyst • Dilute acid + Metal Salt + Hydrogen • Dilute sulphuric acid + Zinc Zinc sulphate + Hydrogen • Zn(s) + 2H2SO4(aq) ZnSO4(aq) + 2H2 (g)
Enzymes are biological catalyst • Enzymes are biological catalyst made of proteins. • Enzymes can alter a chemical reaction, without itself being chemically changed at end of reaction.
Where can we find enzymes? • Enzymes can be taken out of organisms, purified and then used in science and industry. • One common use in the home is in biological washing powders. These contain amylase, lipases and proteases and break down any stains that contain carbohydrate, fat and protein. They therefore digest “biological” stains from the clothes. Since enzymes work at a low temperature this saves electricity and makes them good for delicate fabrics. • Some people, however, are allergic to the enzymes and suffer skin problems.
Enzymes • Advantages of enzymes? • allows reactions to be carried out at lowertemperature • speeds up reaction
Name an example of an enzyme catalysed process What are enzymes? Enzymes
Biological catalysts made of proteins Example of enzyme catalysed process: Digestion Detergent alter rate of chemical reactions remain chemically unchanged at the end of a reaction Enzymes
What’s next? • characteristic of enzymes • explain enzyme action in terms of the ‘lock and key’ hypothesis.
Q&A 1. Which organic compounds are enzymes made up of? • A Protein • B Starch • C Lipid • D Carbohydrate
Q&A • 2. An enzyme speeds up a chemical reaction in the cell, but can only be used once. • A True • B False
How does enzymes work? • How does enzymes increase the rate of reaction?
How does enzymes work? • Substrates: Substances that enzymes work on • The substrate binds with the enzyme active site and an enzyme substrate complex is formed. • The substrate is broken down into a product and is released from the active site. The active site is now free to accept another substrate molecule.
Characteristics of Enzymes • Enzymes speed up chemical reactions. • Enzymes are required in minute amounts • Enzymes are specific [Lock & Key analogy]
Q&A 2. Any substance that is acted upon by an enzyme is called a(n) • A substrate • B amino acid • C active site • D product
Q&A • 3. Here are some stages of an enzyme controlled reaction • An enzyme substrate complex is represented by diagram • A. A • B. B • C. C • D. D