List the major groups of micro-organisms.

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  1. Microorganisms are very small-sized organisms that cannot even be seen by humans with unaided eyes.
  2. Microorganisms exist all over our surroundings.
  3. Some of these can survive in conditions where life seems impossible for us.
  4. Microorganisms are beneficial and harmful to us because they cause diseases in plants and animals.
  5. Microorganisms can be both unicellular and multicellular.
  6. The major groups of microorganisms are the following:
  • Bacteria:
  1. According to the classification, these belong to the kingdom of Monera.
  2. All bacteria are unicellular. But these are prokaryotic (primitive types of cells).
  3. These can be found in temperatures ranging from more than 100 degrees Celsius to less than 0 degrees Celsius.
  4. These can survive in such unfavorable conditions.
  5. Some bacteria also act as pathogens in the human body, like Salmonella typhi.
  6. Some are beneficial to us. For example, a group of bacteria can do photosynthesis.
  7. These are also unicellular but have eukaryotic cells.

  • Protista:
  1. These are also unicellular but have eukaryotic cells.
  2. Some of the organisms are autotrophic and do photosynthesis. Example. Euglena.
  3. Some of these are pathogens in humans and cause serious illness. For example, a flagellated protozoan causes sleeping sickness.
  • Fungi:
  1. These are multicellular with an exception (yeast). Many cells form fungal hyphae and form a web called mycelium.
  2. Some members of fungi cause diseases; some are used as food; even some are used for antibiotic production.
  3. The well-known unicellular fungal yeast is used for fermentation in wineries and bakeries.

  • Algae:
  1. In this group of microbes, autotrophic organisms are included.
  2. These microbes are both multicellular and unicellular.
  3. These are eukaryotic.
  4. These are primitive types of plants with an unorganized body structure.
  5. Some exist as single cells, while some in colonies.
  6. Algae are very beneficial for humans because they do photosynthesis and can also be used to eat.

  • Viruses
  1. Viruses are considered the link between living and non-living things.
  2. These are acellular because they do not have cellular organizations.
  3. Viruses are made up of protein and nucleic acid.
  4. These can infect the host cells but can not live independently.
  5. These cause diseases like the common flu, AIDS, and chickenpox

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