Model organism
From Wikipedia, the free encyclopedia
A model organism is a species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the organism model will provide insight into the workings of other organisms. In particular, model organisms are widely used to explore potential causes and treatments for human disease when experimentation on humans would be unfeasible or unethical. This strategy is made possible by the theoretical common descent of all living organisms, and the conservation of metabolic and developmental pathways and genetic material over the course of evolution.
Image:Drosophila melanogaster - side (aka).jpg
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[edit] Selecting a model organism
Often, model organisms are chosen on the basis that they are amenable to experimental manipulation. This usually will include characteristics such as; short life-cycle, techniques for genetic manipulation (inbred strains, stem cell lines, and transfection systems), and non-specialist living requirements. Sometimes, the genome arrangement facilitates the sequencing of the model organism's genome, for example, by being very compact or having a low proportion of junk DNA (e.g. yeast, Arabidopsis, or pufferfish).
When researchers look for an organism to use in their studies, they look for several traits. 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 from a wider assortment of lineages on the tree of life.
[edit] The use of model organisms
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).
In eukaryotes, several yeasts, particularly Saccharomyces cerevisiae ("baker's" or "budding" yeast), have been widely used in genetics and cell biology, 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 is regulated by homologous proteins. The fruit fly Drosophila melanogaster is studied, again, because it is easy to grow for an animal, has various visible congenital traits and has a huge cell nuclei in its salivary glands that can be examined under a light microscope. The roundworm Caenorhabditis elegans is studied because it has very defined development patterns involving fixed numbers of cells, and it can be rapidly assayed for abnormalities.
[edit] Model organisms used for specific research objectives
[edit] Sexual selection and sexual conflict
- Callusobruchus maculatus, the bruchid beetle
- Chorthippus parallelus, the meadow grasshopper
- Coelopidae - seaweed flies
- Diopsidae - stalk-eyed flies
- Drosophila spp. - fruit flies
- Gryllus bimaculatus, the field cricket
- Scathofaga stercoraria, the yellow dung fly
[edit] Hybrid zones
[edit] References
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[edit] See also
- Animal model
- Ensembl genome database of model organisms
- Animals in space
[edit] External links
| Major Model Organisms in Genetic Studies |
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| Lambda phage | E. coli | Chlamydomonas | Tetrahymena | Budding yeast | Fission yeast | Neurospora | Maize | Arabidopsis | C. elegans | Drosophila | Zebrafish | Rat | Mouse |
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