Site author Richard Steane
The BioTopics website gives access to interactive resource material, developed to support the learning and teaching of Biology at a variety of levels.
Specialists divide microbiology according to their interests, as follows :
Fill in the names in the table below.
|Main groups of micro-organisms||Study called||Specialist called|
(not really living organisms like the rest)
|possibly less important
|algae||algology (phycology)||algologist (phycologist)|
Each of these groups includes organisms which can be seen to be useful to man (especially in the context of biotechnology), and others which are harmful (mainly because of diseases - of animals and plants, or spoilage - of stored products, especially food). There are broad similarities in the way that these micro-organisms grow, but there are distinct differences in detail which must be appreciated.
From a classification point of view, these micro-organisms are now thought to merit separating from other more familiar living organisms (Plants and Animals), so they have been given Kingdoms of their own:
|Group of micro-organism||Kingdom|
|Bacteria and Blue-green "algae"||Monera|
|Protozoa and Algae||Protoctists (Protists)|
(as a separate Kingdom, not a subdivision of the plants)
Pathogens can be said to be parasitic because they live at the expense of the other organism - their "host".
All viruses are pathogenic because they enter cells and cause adverse effects. Some of the worst diseases of Man are viral, i.e. caused by a virus.
Some bacteria (ones which cause headlines!) are pathogenic, and a few cause quite serious diseases. Other bacteria seem to be useful to Man in their correct contexts, whilst other apparently fairly harmless bacteria may cause diseases in certain circumstances, e.g. old or young people. In addition, there may be different varieties or strains (especially of bacteria and viruses) which show different characteristics from the normal type or species.
Similarly, there are examples of protozoans (protoctists) and fungi which are pathogenic.
Reproductive potential: Because they can multiply rapidly, it only takes a few bacteria or viruses to cause an infection. Usually, micro-organisms reproduce asexually, so they can produce millions in a few hours.
Variability: With such large potential populations, new varieties can arise due to mutation, and characteristics like resistance to antibiotics can spread easily, even between unrelated species!
Insidiousness: They cannot be seen directly, and whilst reproducing and preparing to spread they can cause great damage to cells and internal working parts of organisms.