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KS4 Biology

Biotechnology

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What is biotechnology?

Living things use chemical reactions to produce new materials.

Biotechnology is the use of these reactions by humans to manufacture useful products.

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Uses of biotechnology

What products are made using biotechnology?

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Biotechnology – an old art

Can you think of some products that have been made using biotechnology for thousands of years?

bread cheese and yoghurt

beer and wine

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Biotechnology

Summary activities

Enzymes

Fermentation

Introducing biotechnology

Contents

Other uses of biotechnology

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What is fermentation?

Yeast cells contain enzymes that converts sugars (such as glucose and sucrose) into alcohol (ethanol) and carbon dioxide.

glucose +ethanolcarbondioxide

C6H12O6 (aq) C2H5OH (l) CO2 (g) +

This reaction is called fermentation.

Fermentation usually takes place at 20-30°C. It must take place in anaerobic conditions (without oxygen) otherwise the ethanol would react with oxygen and turn into vinegar.

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Fermentation in the lab

How can fermentation be shown to create carbon dioxide?

sugar solution and yeast

water bath at 35 °C

limewater

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Uses of fermentation

Fermentation has been used for thousands of years in brewing and baking.

Alcoholic drinks such as beer and wine are made by adding yeast to sugary solutions.

Bread rises due to the production of bubbles of carbon dioxide in the fermenting dough. A froth of CO2 and yeast

during fermentation

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The enzymes in the yeast convert the glucose to alcohol.

The juice is fermented under anaerobic conditions by the

natural yeast on the grape skins.

Grapes are crushed to release their juice, which contains the glucose.

Grapes convert carbon dioxide to glucose by photosynthesis.

Fermentation and wine-making

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Beer is usually filtered and the yeast recycled to make more beer.

Yeast is added and enzymes in this convert the sugar to alcohol.

Hops are added for flavour.

Barley is boiled with waterto release the sugar.

Barley grains are warmed with water to germinate. This produces sugar.

Fermentation and beer-making

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The beer-making process

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The bread is baked, killing the yeast and evaporating the alcohol. Holes are left in the mixture where

the CO2 gas expanded.

Fermentation produces carbon dioxide gas, which makes the dough rise.

The dough is left in a warm environment to allow fermentation.

Flour is mixed with water, yeast, salt and sugar to make a dough.

Fermentation and bread-making

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Fermentation

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Biotechnology

Summary activities

Enzymes

Fermentation

Introducing biotechnology

Contents

Other uses of biotechnology

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The enzyme lactase from the bacteria convert milk sugar (lactose) into lactic

acid, which gives a sour taste and makes the product semi-solid.

The milk is mixed with specially-cultured bacteria and kept warm.

Pasteurized or sterilized milk is used to kill unwanted bacteria.

Making yoghurt

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The yoghurt-making process