Model organism

From Academic Kids

A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workings of other organisms. This is possible because fundamental biological principles such as metabolic, regulatory, and developmental pathways, and the genes that code for them, are conserved through evolution.

There are many model organisms. The first model organism for molecular biology was probably the bacterium Escherichia coli which is common in the human digestive system (and usually beneficial -- the dangerous E. coli O157:H7 is a rare strain). This also led to a study of many bacteriophages, particularly phage lambda.

In eukaryotes, several yeasts, particularly Saccharomyces cerevisiae ("baker's" or "budding" yeast), have been widely studied, largely because they are quick and easy to grow. The cell cycle in a simple yeast is very similar to the cell cycle in humans, and regulated by homologous proteins. The fruit fly Drosophila melanogaster was studied, again because it was easy to grow for a multicellular organism. The roundworm Caenorhabditis elegans is studied because it has very defined development patterns and can be rapidly assayed for abnormalities.

When researchers look for an organism to use in their studies, they look for several traits. Common among these are size, generation time, accessibility, manipulation, genetics, conservation of mechanisms, and potential economic benefit. As comparative molecular biology has become more common, some researchers have sought model organisms that represent assorted lineages of life.


Important model organisms



Unicellular eukaryotes

Multicellular eukaryotes





  • Cavius porcellus, the guinea pig, used by Robert Koch and other early bacteriologists as a host for bacterial infections, hence a byword for "laboratory animal" even though rarely used today.
  • Rat (Rattus norvegicus) - particularly useful as a toxicology model; also particularly useful as a neurological model and source of primary cell cultures, owing to the larger size of organs and suborganellar structures relative to the mouse.
  • Mouse (Mus musculus) - the classic model vertebrate
  • Zebrafish (Brachydanio rerio), a freshwater fish, has a nearly transparent body which provides unique visual access to the animal's internal anatomy throughout its life. Zebrafish are used to study development, toxicology and toxicopathology1, specific gene function and roles of signaling pathways.
  • Xenopus laevis, the African clawed toad, also used in development
  • Takifugu rubipres, a pufferfish - has a small genome with little junk DNA
  • Dog (Canis lupus familiaris) - an important respiratory and cardiovascular model
  • Homo sapiens, human beings, which are capable of self-reporting and have the largest catalog of known genetic disorders


Note 1: Spitsbergen J.M. and Kent M.L. (2003). The state of the art of the zebrafish model for toxicology and toxicologic pathology research--advantages and current limitations. Toxicol Pathol. 31 (Supplement), 62-87. PubMed Abstract Link => PMID 12597434. Note 2: Riddle, Donald L.; Blumenthal, Thomas; Meyer, Barbara J.; and Priess, James R. (Eds.). (1997). C. ELEGANS II. Woodbury, NY: Cold Spring Harbor Press. ISBN 0-87969-532-3. Full text available on-line (

Related topics

External links

de:Modellorganismus nl:modelorganisme


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