Biotechnology involves using living organisms to carry out processes that make substances that we want.

Using microorganism

​Why?

1. Bacteria are very small and are easy to grow in a laboratory. They do not take up a lot of space.

2. Bacteria reproduce very quickly.

3. Bacteria can make complex molecules that are useful to humans.

4. No one minds what is done to bacteria and fungi. There are few ethical issues

Using microorganism

​Why?

• As well as their ‘main’ DNA – their ‘chromosome’ – bacteria also have little loops of DNA called plasmids. These are quite easy to transfer from one cell to another.

Yeast is a single-celled fungus.

Yeast is able to respire anaerobically.

glucose ➞ ethanol + carbon dioxide

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Making use of anaerobic respiration in yeast

​​Making biofuels

​​Making bread

Making use of anaerobic respiration in yeast

glucose ➞ ethanol + carbon dioxide

One alternative to fossil fuel is to use plants to provide sugars, which yeast can then break down to form ethanol. The ethanol – sometimes called bioethanol/biofuel – can then be used as a fuel.

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Using biofuel to replace fossil fuel

1. Does not contain as much energy per litre as fossil fuels.

2. Put up food price

Sustainable

​Advantages

​Disdvantages

Flour contains a lot of starch, and also protein – especially a protein called gluten. To make bread, the flour is mixed with water and yeast to make dough.

Making bread

Amylase enzymes break down some of the starch in the dough to make maltose and glucose, which the yeast can use in anaerobic respiration. It produces bubbles of carbon dioxide. These get trapped in the dough. Gluten makes the dough stretchy, so the carbon dioxide bubbles cause the dough to rise

Pectinase

​​Biological washing powder

Making use of enzymes

Lactase

Fruit juices are extracted using an enzyme called pectinase.

Pectin is a substance which helps to stick plant cells together. Pectinase breaks down pectin. This makes it much easier to squeeze juice from the fruit.

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​Pectinase

Pectinase also helps to make the juice clear rather than cloudy (Figure 20.5). The cloudiness in fruit juice is often caused by insoluble carbohydrates that float in the juice.

Pectinase and other enzymes such as cellulase (which breaks down cellulose) break the insoluble substances to soluble ones, so the juice becomes clear.

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​Pectinase

Biological washing powder

• Biological washing powders contain enzymes, as well as detergents. These enzymes help to break down other kinds of substances which can stain clothes.

• To prevent these enzymes from digesting proteins and fats in the skin of people handling them, the enzymes are packed into microscopic capsules

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Lactase

Lactase is an enzyme that breaks down lactose, the sugar found in milk.

Lactose---> glucose + galactose

Some people – for example, those of European descent – continue to make lactase all of their lives. However, most people – for example, those of Asian descent – stop making lactase when they are adults. These people cannot digest lactose. They may feel ill if they eat or drink foods that contain lactose.

Milk can be treated with lactase to break down the lactose, so that people who don’t make lactase themselves can drink milk or eat products made from the lactose-free milk

Growing microorganisms in a fermenter

Growing microorganisms in a fermenter

Sterilisation (kill microorganisms)---->Add air and nutrients--->mixing the content------>Add microorganisms--->measuring temperature and pH---> Harvest--->purifying the products

Many different substances are now produced commercially using fermenters. These include:

•insulin, made by genetically modified bacteria

•the antibiotic penicillin, produced by the fungus Pencillium

•a food called mycoprotein, produced by a fungus called Fusarium