Microbiology comes from the Greek words ‘mīkros’ and ‘bios’ which mean ‘small life.’ Microbiology is the study of microscopic organisms, either unicellular, multicellular, or acellular (no cells). Microbiology includes numerous sub-disciplines including virology, mycology, parasitology, and bacteriology.
Eukaryotic microorganisms possess membrane-bound cell organelles and include fungi and protists. Prokaryotic organisms—which all are microorganisms—are conventionally classified as lacking membrane-bound organelles and include eubacteria and archaebacteria. Microbiologists traditionally have to rely on culture, staining, and microscopy. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means. Microbiologists often rely on extraction or detection of nucleic acid, either DNA or RNA sequences.
Viruses have been variably classified as organisms. They have been considered either very simple microorganisms or very complex molecules. Prions, which are never considered microorganisms, have been investigated by virologists, however, as the clinical effects traced to them were originally presumed due to chronic viral infections, and virologists took search—discovering “infectious proteins”.
As an application of microbiology, medical microbiology is often introduced with medical principles of immunology as microbiology and immunology. Otherwise, microbiology, virology, and immunology as basic sciences have greatly exceeded the medical variants, applied sciences.