1. KS4 Biology
Biotechnology 1

2. 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. 2

3. Uses of biotechnology What products are made using biotechnology?
There are several items in the image that rely on biotechnology:
biological washing powder – use of lipases, proteases and carbohydrases to break down fat, protein and carbohydrate stains
beer – production of alcohol by fermentation
wine – production of alcohol by fermentation
bread – production of carbon dioxide by fermentation
cheese – conversion of lactose to lactic acid, and production of curd
yoghurt – conversion of lactose to lactic acid
baby food – use of proteases to ‘pre-digest’ the food
penicillin – the mould Penicillium notatum is used industrially to produce the antibiotic penicillin
soft-centred chocolates – the centres initially start off hard and mainly contain sucrose; over time this is broken down by invertase to produce simpler sugars and so make the centre soft and runny
stone-washed denim – cellulase and other enzymes are used to remove some of the dye from the denim and abrade the material to give a faded, worn appearance
plants – bacteria are used to transfer disease-resistance and other genes into plants 3

4. 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 4

5. Biotechnology Introducing biotechnology Enzymes Fermentation
Contents
Biotechnology
Introducing biotechnology
Enzymes
Fermentation
Other uses of biotechnology
Summary activities 5

6. + + What is fermentation?
Yeast cells contain enzymes that converts sugars (such as glucose and sucrose) into alcohol (ethanol) and carbon dioxide.
glucose  +
ethanol
carbon dioxide
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. 6

7. sugar solution and yeast
Fermentation in the lab
How can fermentation be shown to create carbon dioxide?
water bath at 35 °C
sugar solution and yeast
limewater 7

8. A froth of CO2 and yeast during fermentation
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.
A froth of CO2 and yeast during fermentation
Bread rises due to the production of bubbles of carbon dioxide in the fermenting dough.
The photograph shows the ‘dirty head’ stage of fermentation. This is the foamy collection of carbon dioxide bubbles, yeast and fermentation by-products of actively-fermenting beer. This foam is also called ‘krausen’.
Image © British Beer & Pub Association 8

9. Fermentation and wine-making
Grapes convert carbon dioxide to glucose by photosynthesis.
Grapes are crushed to release their juice, which contains the glucose.
The juice is fermented under anaerobic conditions by the natural yeast on the grape skins.
The enzymes in the yeast convert the glucose to alcohol. 9

10. Fermentation and beer-making
Barley grains are warmed with water to germinate. This produces sugar.
Barley is boiled with water
to release the sugar.
Hops are added for flavour.
Yeast is added and enzymes in this convert the sugar to alcohol.
Beer is usually filtered and the yeast recycled to make more beer. 10

11. The beer-making process11

12. Fermentation and bread-making
Flour is mixed with water, yeast, salt and sugar to make a dough.
The dough is left in a warm environment to allow fermentation.
Fermentation produces carbon dioxide gas, which makes the dough rise.
The bread is baked, killing the yeast and evaporating the alcohol. Holes are left in the mixture where the CO2 gas expanded. 12

13. Fermentation 13

14. Biotechnology Introducing biotechnology Enzymes Fermentation
Contents
Biotechnology
Introducing biotechnology
Enzymes
Fermentation
Other uses of biotechnology
Summary activities 14

15. Making yoghurt
Pasteurized or sterilized milk is used to kill unwanted bacteria.
The milk is mixed with specially-cultured bacteria and kept warm.
The enzyme lactase from the bacteria convert milk sugar (lactose) into lactic acid, which gives a sour taste and makes the product semi-solid. 15

16. The yoghurt-making process16