ocr-b4-lesson 2 enzymes and ph
TRANSCRIPT
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Learning outcomessummarise the role of enzymes in living organismsdescribe enzyme action in terms of active site shapedescribe the effect of pH on enzyme activity
Keywords- enzyme, pH, active site, enzyme action, catalyst, reactants, products, Lock and key model.
Enzymes and pH
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What do you know about enzymes?
Write a list
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In B2 we learned that:Enzymes are proteins that speed up chemical reactions, in the context that genes determine which proteins are made in cells.
Enzymes can be thought of as catalysts as well as agents that break large molecules into smaller ones
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What effect does catalase (in celery) have on hydrogen peroxide?Discuss the role of catalase in cells.
What is hydrogen peroxide?
H2O2
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Watch the demonstration of the reaction of catalase and hydrogen peroxide
Then carry out your investigationYou will consider the effect of different pH levelsEach group will carry put two (2) investigations and results will be added to the board
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As a class we carried out a practical, looking at the effect of enzymes on pH. We started with 3 buffer solutions of pH 4, pH 7 and pH 9. we used yeast as the catalase and added this to the hydrogen peroxide, collecting the oxygen produced.
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What can we conclude from out results
What happens?????????
What ‘reactants’ and ‘products’ in the context of this particular enzyme.
Catalase + hydrogen peroxide oxygen and water
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An enzyme
A computer graphic of an enzyme, its active site, and the product of a reaction
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How does the enzyme speed up the reaction? look at the first two screens of Animation IB4.2.4 Enzymes introducing the idea of the lock-and-key model.complete Activity AB4.2.2 Lock-and-key model using Textbook Section B and Animation IB4.2.4 Enzymes.
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Enzyme animations
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Your core body temperature is about 37°C, but a small variation either side of this is normal. a core temperature over 42°C or under 28°C usually results in death.
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Around 80% of the energy from your food is used for keeping warm
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Shrews have a large surface area for their volume. They lose heat to the environment over their whole body surface. To release enough energy to maintain their body temperature, they have to eat 75% of their body mass in food each day.