By Cora McSwiney 8Or

What Are Micro-Organisms?

Micro-Organisms come in five main categories: bacteria, virus, protozoon, algae and fungus. There are over 1 million bacteria types, and counting, and over 65,000 protozoon types. The virus, considered the most vicious of the five, can also be used to help biology study.

What do Micro-Organisms have in them?

Usually, a Micro-Organism only has a single cell in it, which is really small considering that on average a human body contains about 100 trillion cells. Depending on the micro-organism, that cell can be of many different types.



Bacteria, like all micro-organisms are microscopic, but are at least 10 x the size of a virus. Bacteria can duplicate itself, but most of the bacteria in our bodies are completely unharmful. The Harmful sort is called Pathogenic Bacteria, and enters the body through water or food. They then attach themselves to cells and reproduce using the human body as nutrition.


A virus (or tiny parasite) affects living organisms. They only cause infection, although some scientists believe that in the future, viruses may be used to kill of other diseases such as cancer. This is the main reason they are keeping the virus cells of smallpox in a freezer underground, even though the disease is deadly, scientists think that there will come a time when the human race will need it to kill of an even deadlier disease.

Protozoon (Protozoa)

Protozoa eat away at other living organisms such as bacteria and other protozoon. Although Protozoa can rid the body of any harmful bacteria, a protozoon can be harmful itself. Some, are even parasites (viruses or harmful germs).


Algae, can range from micro-organisms to huge clumps of seaweed. Whilst usually found in damp places or water, algae relies completely on photosynthesis (the transformation of sun into energy or nutrition)


Yeasts, Moulds and mushrooms are all fungi. Fungi have cells with thin walls, which contain chitin, which contains cellulose, the main chemical that forms the structure of plants.

information from: Wikipedia, The Life Fantasy Land and BBC Bitesize.