N.52 – Short course of microbiology for environmentalist


Text from “The Society for General Microbiology U.K.”


Microbe An organism that can only be seen clearly under a microscopy
Eukariote An organism made of cells which contain membrane-bound organelles such as nuclei
Prokariote An organism made of a cell which lacks membrane-bound organelles such as nuclei, e,g. bacteria and archea
Bacterium A unicellular prokaryote with a cell wall made from peptidoglycan; bacteria (plural) make up one of the 3 domain life
Archean A unicellular prokaryote similar to bacteria; archea (plural) make up one of the 3 domains of life
Eukarya One of the 3 domain of life; contains all eukaryotes, including plants, animals, fungi and other organisms that were previously classified as Protoctista in 5 kingdom system


Kingdom The highest rank in the hierarchy of the 5 kingdom system are Prokariotae, Animalia, Plantae, Fungi and Protoctista
Domain A category of organisms; all organisms can be classified in one of 3 domains Eukarya, Prokarya and Archaea
Classification The arrangement of organisms into groups
Taxonomy The process of naming and classifying organisms
Phenetic classification A method of arranging organisms based on properties such as anatomy or morphology (i.e. the 5 kingdom system)
Phylognetic classification A method of arranging organism based on evolutionary relationship between organisms (i.e. the 3 domain system)


Chromosome An organized structure of DNA (and often) protein); contains genes
Plasmid A circular piece of DNA separate from the chromosome of a bacterium
Conjugation The transfer of DNA from one cell to another via direct cell to cell contact
Asexual A type of reproduction that does not depend on sex cells or sex organs
Binary fission A type of asexual reproduction in which a single-celled organism divides to produce two daughter cells of the same size
Budding A type of asexual reproduction in which a new cell or appendage is formed from an outgrowth of a cell; occurs in microbes such as yeast and some plants and animals


Capsule A protein or polysaccharide layer external to the cell wall; found in some prokaryotic cells
Endospore A dormant non-reproductive structure formed inside some bacterial cells, often in response to environmental conditions; many are able to survive extreme temperatures, radiation and desiccation and will develop into bacterial cells when conditions become more favourable
Flagellum A long filament sticking out of a cell that enables movement; in bacteria it moves with a cork screw motion due to the rotation of a flagellar motor anchored in the cell membrane
Pilus A protein filament protruding from the surface of some bacterial cells (similar to a fimbria); some are involved in conjugation
Fimbria A protein filament protruding from the surface of some bacterial cells (similar to a pilus)
Ribosome A structure made of protein and RNA, that is the site of protein synthesis


Peptidoglycan A polymer found in the cell walls of bacteria
Gram Stain A method that stains bacteria differentially according to their cell wall structure
Gram-negative Bacteria with cell walls made of 10% peptidoglycan plus an additional lipopolysaccharide layer; they stain pink or red with Gram’s reagent
Gram-positive Bacteria with cell walls made of 90% peptidoglycan; they stain purple with Gram’s reagent
Glycocalyx Slim or gummy material secreted on the outside of some bacterial cells, e.g. a slime layer or capsule
Slime layer A gummy layer external to the cell wall that is found in some prokaryotic cells; unlike a capsule it is diffuse and easily removed


Fungus A eukaryotic organism with a cell wall made from chitin; can be unicellular (e.g. yeast) or multicellular (e.g. moulds)
Yeast A unicellular fungus; used widely in biotechnology
Hypha A thread-like fungal filament which forms branching networks called mycelia
Mycelium A mass of fungal filaments (hyphae)
Spore (fungal) A single-celled or multicellular structure produced for dispersal, as a result of sexual or asexual reproduction or in response to adverse conditions
Fruiting body A structure made by filamentous fungi in order to produce and release spores; they are commonly known as mushrooms and toadstool


Virus An acellular infectious agent consisting of a protein coat and nucleic acid core
Virion A virus particle consisting of a protein coat called a capsid and a core (containing a nucleic acid) called the nucleocapsid
Envelop (viral) A phospholipid bilayer on the outside of certain viruses
Capsid The protein coat that surrounds the nucleic acid genome of a virus
Nucleocapsid The core of a virus; contains the RNA or DNA genome
Lytic cycle The life cycle of a virus during which it replicates continually, destroying the host and releasing virl particles