Microorganisms

Outcomes

To write a definition of a micro-organism.
Describe examples of beneficial micro-organisms.
Describe examples of harmful micro-organisms.
To explain how micro-organisms play an important role as decomposers in an ecosystem

Beneficial microorganisms

Some microbes are used for medicinal production. One of the most important groups of medicines, antibiotics, is produced by fungi and bacteria. The name antibiotics means 'against life'. It is appropriate, because they attack bacteria and other unicellular organisms that are pathogenic for humans.

Harmful microorganisms

Although every microbe is not harmful and pathogenic, still there exist numerous fatal microorganisms in the environment. Microorganisms include bacteria, fungi, viruses, and protozoa. They are very small but they can cause diseases and even lead to death. Some of them are free-living but some are parasites.

A microorganism or microbe is an organism which is microscopic, making it too small to be seen by the unaided human eye.

The study of microorganisms is called microbiology.

Microorganisms include bacteria, fungi, archaea, protists and viruses.

What are microorganisms?

Microorganisms are very tiny living things. They are so small that you need a microscope to see them.

Microorganisms are all around us, in the air, in our bodies and in water. Some microorganisms are harmful to us, but others are helpful to us.

There are three types of microorganism:

viruses
bacteria
fungi

Harmful microorganisms

Microorganisms that cause diseases are often called germs.

Some diseases, like chickenpox, are caused by viruses. Diseases caused by viruses usually spread easily from one person to another.

Uncooked foods (especially meat) can contain bacteria. The bacteria are killed when the food is cooked properly. But if you eat food that has not been cooked properly, the bacteria may survive and make you feel very ill.

Bacteria left in your mouth by not brushing your teeth properly can cause a tooth infection. Bacteria left in your mouth could also cause an infection in your ear.

Mould is a type of microorganism that grows on decaying food. It can make you ill if you eat it.

Helpful microorganisms

Here are some examples of useful microorganisms.

When bread is made, a microorganisms called yeast is added to the dough to make the bread rise.

Yoghurt is made by boiling milk and adding special bacteria to it. The bacteria turn the sugar in the milk into acid. The acid makes the milk go thick and stops any harmful bacteria growing.

Inside a pile of dead leaves are millions of tiny bacteria. These bacteria feed on the leaves and break them down into nutrients. The nutrients go back into the soil where they can be used by plants.

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