Microorganisms are organisms that can't be seen with the naked eye. They can be seen with the use of a microscope.
Microorganisms are categorised into two groups namely unicellular and multicellular microorganisms.
Unicellular microorganisms are single celled mocroorganisms with a simple structure. Examples are bacteria and archaea.
They are further divided into two groups namely prokaryotes and eukaryotes.
Prokaryotes are unicellular microorganisms that do not have a membrane that protects their nucleus or any organelles in the cell. Examples are bacteria and archaea
Eukaryotes are unicellular microorganisms which have thier organelles protected by membranes.
Examples are yeast and amoeba.
Multicellular microorganisms are made up of more then one cell. They are more complex in structure compared to unicellular microorganisms. Examples include plants, animals, fungi etc.
Microorganisms have known to be in constant relationship in man as they have been know to have both positive and negative effects.
For instance, the spoilage of food is caused by a microorganism named pseudomonas . Also penicillin used in wound treatment is made from a microorganism called a mould.
Microorganisms can be a friend or foe depending on the effect they produce. That's how I define a microorganism.
