Model organism

Drosophila melanogaster, one of the most famous subjects for genetics experiments
Saccharomyces cerevisiae, one of the most intensively studied eukaryotic model organisms in molecular and cell biology

A model organism (often shortened to model) is a non-human 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.[1][2] Model organisms are widely used to research human disease when human experimentation would be unfeasible or unethical.[3] This strategy is made possible by the common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution.[4]

Studying model organisms can be informative, but care must be taken when generalizing from one organism to another.[5][page needed]

In researching human disease, model organisms allow for better understanding the disease process without the added risk of harming an actual human. The species chosen will usually meet a determined taxonomic equivalency[clarification needed] to humans, so as to react to disease or its treatment in a way that resembles human physiology as needed. Although biological activity in a model organism does not ensure an effect in humans, many drugs, treatments and cures for human diseases are developed in part with the guidance of animal models.[6][7]

There are three main types of disease models: homologous, isomorphic and predictive. Homologous animals have the same causes, symptoms and treatment options as would humans who have the same disease. Isomorphic animals share the same symptoms and treatments. Predictive models are similar to a particular human disease in only a couple of aspects, but are useful in isolating and making predictions about mechanisms of a set of disease features.[8]

There are many model organisms. One of the first model systems for molecular biology was the bacterium Escherichia coli, a common constituent of the human digestive system. Several of the bacterial viruses (bacteriophage) that infect E. coli also have been very useful for the study of gene structure and gene regulation (e.g. phages Lambda and T4). However, it is debated whether bacteriophages should be classified as organisms, because they lack metabolism and depend on functions of the host cells for propagation.[9]

Model organisms are drawn from all three domains of life, as well as viruses. Examples include Escherichia coli (E. coli), baker's yeast (Saccharomyces cerevisiae), the T4 phage virus, the fruit fly Drosophila melanogaster, the flowering plant Arabidopsis thaliana, guinea pigs (Cavia porcellus), and the mouse (Mus musculus).

  1. ^ Fields, S.; Johnston, M (2005-03-25). "CELL BIOLOGY: Whither Model Organism Research?". Science. 307 (5717): 1885–1886. doi:10.1126/science.1108872. PMID 15790833. S2CID 82519062.
  2. ^ Griffiths, E. C. (2010) What is a model? Archived March 12, 2012, at the Wayback Machine
  3. ^ Fox, Michael Allen (1986). The Case for Animal Experimention: An Evolutionary and Ethical Perspective. Berkeley and Los Angeles, California: University of California Press. ISBN 978-0-520-05501-8. OCLC 11754940 – via Google Books.
  4. ^ Allmon, Warren D.; Ross, Robert M. (December 2018). "Evolutionary remnants as widely accessible evidence for evolution: the structure of the argument for application to evolution education". Evolution: Education and Outreach. 11 (1): 1. doi:10.1186/s12052-017-0075-1. S2CID 29281160.
  5. ^ Slack, Jonathan M. W. (2013). Essential Developmental Biology. Oxford: Wiley-Blackwell. OCLC 785558800.
  6. ^ Chakraborty, Chiranjib; Hsu, Chi; Wen, Zhi; Lin, Chang; Agoramoorthy, Govindasamy (2009-02-01). "Zebrafish: A Complete Animal Model for In Vivo Drug Discovery and Development". Current Drug Metabolism. 10 (2): 116–124. doi:10.2174/138920009787522197. PMID 19275547.
  7. ^ Kari, G; Rodeck, U; Dicker, A P (July 2007). "Zebrafish: An Emerging Model System for Human Disease and Drug Discovery". Clinical Pharmacology & Therapeutics. 82 (1): 70–80. doi:10.1038/sj.clpt.6100223. PMID 17495877. S2CID 41443542.
  8. ^ "Pinel Chapter 6 - Human Brain Damage & Animal Models". Archived from the original on 2014-10-13. Retrieved 2014-01-10.
  9. ^ Grada, Ayman; Mervis, Joshua; Falanga, Vincent (October 2018). "Research Techniques Made Simple: Animal Models of Wound Healing". Journal of Investigative Dermatology. 138 (10): 2095–2105.e1. doi:10.1016/j.jid.2018.08.005. PMID 30244718.

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