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Microorganisms: Definition, Classification and Facts

Do you know about microorganisms? How they look like? What are the functions of microorganisms? What is the classification of microorganisms?  Let us have a Look!
Aug 22, 2019 18:43 IST
What are Microorganisms?

As name suggest those organisms that are seen through microscope or microscopic organisms are known as microorganisms or microbes. They are found all around us and you will be amaze to know that they are found inside our bodies also. So, we can say that microorganisms are so small that usually we require a microscope to see them.

Let us tell you that vast majority of microorganisms does not pose any harm or threat to humans, plants or animals. In fact they work alongside humans to make world go round like they help in decomposition, decay and also help us to digest food in our body. But we can't ignore the fact that there are also some microorganisms which pose negative impact or harm us, our lives like they cause illness, bad odours, can even damage certain products, surfaces etc. Some common names of microorganisms that we mostly hear are Salmonella, E.Colli, MRSA, Malaria, Bird flu.

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Classification of Microorganisms

There are various types of microorganisms like bacteria, fungi, viruses, algae, archae and protozoa.

Bacteria: Bacteria are the most common microorganism that we hear mostly in our daily lives Isn't it! They are the member of prokaryotes. They does not have nucleus inside the cell and does not contain organelles. So, mainly they are specialised cellular organs. Bacteria consists of two classes namely Gram positive bacteria which consists thicker cell wall and another is Gram negatives which have a thinner layer which is sandwiched between an inner and outer membrane.

Note: It is said that Bacteria does not pose any harm and can live harmlessly within the human body and are the most successful organism on the Earth. They also help in the body function like digestion. Few bacteria may be dangerous also.

Fungi: They are eukaryotes which have defined nucleus and organelles. Do you know that the cells of fungi are larger than prokaryote that is bacteria? When fungi achieved a certain level of growth, they are visible via eye like a mould on bread.

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Fungi are divided into three main groups:

  1. Moulds that display thread-like growth and are multicellular in structure.
  2. Yeasts which are non-filamentous and can be single celled.
  3. Mushrooms which has fruiting body for production of spores.

Fungus consists of pathogens which can cause disease in plants. In fact in the food industry, for production of bear etc. fungi is used.

Viruses: According to various experts viruses are not living organisms. They consist of nucleic acid that is DNA or RNA and a protein coat. Basically, a virus requires a host cell for replication. Virus enters the human beings and enters in the cell where they replicate.

It depends upon the immune system of the body. If immune system is weak then virus may affect the human being and may cause disease like common cold, influenza etc. In fact some virus may cause permanent and irreversible damage to the cells of human beings for example HIV.

Algae: According to some definitions algae consists of prokaryotes and eukaryotes both. Algae, unlike other microorganisms are photosynthesisers and are typically found in marine environments. Prokaryotic algae are known as Cyanobacteria or blue-green algae. But some says that algae are eukaryotes only that is they are small aquatic plants.

So, now you may have come to know about microorganisms and their types.

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