Introduction To Microbiology

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Microbiology is the study of micro organisms such as bacteria, fungi, protozoa and viruses. Many of these organisms are beneficial for human beings. In humans normal microbiota which helps in digestion. While in plants nitrogen fixation which helps in cellulose digestion. Also these microorganisms are used in the industries.


We divide these micro organisms according to their characteristics:

  1. Bacteria
  2. Viruses
  3. Fungi
  4. Protozoa


We use gram stain either positive or negative to characterize them.


We depend on their genome in order to characterize them. That is Double stranded sd RNA/DNA & SS DNA.


We characterize fungi into Mold (Multicellular) & Yeast (Unicellular).


Some protozoan species are parasites and some are predators of bacteria and algae.

Hierarchy of Classification

  1. Domain
  2. Kingdom
  3. Phylum
  4. Class
  5. Order
  6. Family
  7. Genus
  8. Species


There are only three main domain on this planet earth.

  1. Prokaryotic: Bacteria Algae
  2. Eukaryotes: Eukarya

Difference b/w Prokaryotic and Eukaryotes:

Prokaryotic: Absence of cytoplasmic structures like mitochondria, Golgi apparatus and endoplasmic reticulum.

Eukaryotes: absense of cell wall except plants and fungi. Also they have different structure of ribosomes.