Microorganisms

Introduction

If you can only see a living thing with a microscope, that means it is a microorganism. These are found everywhere.
Some of them, like yeast are helpful. And some of them are harmful and disease causing, like bacteria. It is important to know how to avoid spreading the bad ones!

This section includes:

What are microorganisms?
Harmful microorganisms
How to avoid spreading harmful microorganisms
Helpful microorganisms

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

microscope

Microorganisms are all around us, in the air, in the soil, 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

Viruses
Viruses can only reproduce inside a living cell.
Average size: 0.0001mm
Structure: A strand of genetic material wrapped in a protein coat.
Uses: To kill pest animals
Diseases: Common cold, influenza (flu), measles, AIDS, yellow fever, rabies,

Bacteria
Most bacteria live in water, soil and decaying material.
Average size: 0.001mm

Structure: Bacteria are single-celled with a strong cell wall. their genetic material is not in a nucleus.

Uses: To make yoghurt, cheese and vinegar.
Diseases:Typhoid, cholera, food poisoning.

bacteria

Fungi
Some fungi are microorganisms, for example yeast and mould. Yeast is made of single cells that reproduce by budding off new cells. Yeast cells are larger than viruses.

yeast

Moulds are fine threads that grow on rotting food; they also give blue cheese its colour and flavour.

blue cheese

Fungi can be helpful: we use yeast to make bread, beer and wine and mould to make antibiotics. they can also be harmful; fungi cause athlete's foot and ringworm.