Model Organism

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What is the Model Organism or Definition of Model Organism?

To define a model organism, it is a non-human species that’s kept in laboratories to aid scientists who understand specific biological processes. Model organisms are used to gain information concerning other species that are difficult to understand. Characteristics of model organisms include easy manipulation, rapid maturity, producing large amounts of offspring, short life span, and more related. There are various model organism definitions and this is one among them.


The human being's disease course disease might take a long time. However, model organisms can develop a disease, and its symptoms can spread rapidly. This helps scientists understand and learn the disease in a shorter period. Thus, model organisms help in examining the cause of newly formed diseases. Over time, in clinical research, model organisms have become essential tools.


Types of Model Organisms

The famous model organisms are given below.


The House Mouse (Mus musculus)

Mouse (Mus musculus) is the most preferred mammalian model organism of many researchers. Mice have numerous advantages as a mammalian model organism for scientists because they have short generation time for mammals relatively - the time between being giving birth and born - of about ten weeks. Adult mice often reproduce as every three weeks and because the scientists simultaneously can observe different generations of mice at a time.


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The Fruit Fly (Drosophila Melanogaster)

Drosophila melanogaster is another popular model organism, or as it is more commonly known as the fruit fly. The fruit fly also has been used in scientific research for over a century. It was taken to the forefront by Thomas Hunt Morgan, the "father" of Drosophila research. Morgan discovered that the genes were found within chromosomes by using the Drosophila melanogaster far before we even knew that DNA was a kind of genetic material.


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Yeast (Saccharomyces Cerevisiae)

Yeast is the simplest eukaryotic organisms and is a commonly used model organism in scientific research. The same kind we use in pieces of bread and other baked goods! Yeast is simple, cheap, and easy to work with as they can survive in different environmental conditions, and gets doubled every 2 hours. Yeast is very amenable to genetic manipulation and also the first eukaryotic genome to be entirely sequenced.


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Zebrafish (Danio Rerio)

Zebrafish have gradually become a famous model organism since the 1960s. They share up to 70% of their genes with humans, and 85% of their genes with humans associated with a disease with a homolog in zebrafish (Howe et al., 2013). Zebrafish are small and easily maintained because they are housed in large groups, easily bred, and produce 50-300 eggs in one instance. Also, the zebrafish embryos are laid and fertilized externally, allowing scientists to manipulate them easily. Scientists can inject one-celled embryos with either RNA/DNA to edit their genomes or create transgenic animals.


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The Worm (Caenorhabditis Elegans)

Caenorhabditis elegans, the worm, has been extensively used as the model organism since the 1970s when the Sydney Brenner brought it into the lab to study neuronal development (Brenner, 1973). These C. Elegans are transparent, small worms with a rapid life cycle and large brood sizes. The majority of C. Elegans are self-fertile hermaphrodites making it easy to conduct extensive experiments over multiple generations. Likewise to other model organisms, the C. Elegans genome is also wholly sequenced, and about 60% of the human genes in C. Elegans have an ortholog, making it ideal for studying the processes of basic molecular biology.


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Characteristics of Model Organisms

A few of the characteristics of model organisms are listed below.

  • Relatively short generation time (Birth → Reproduction → Birth).

  • Relatively easy to maintain and grow in a restricted space.

  • Relatively easy to provide necessary nutrients for growth.

  • Relatively well-understood development and growth.

  • Closely resemble other organisms or systems.

  1. Mammalian Models

  • Rat (Rams norvegicus) 

  • Mouse (Mus muscu/us)

  1. Non - Mammalian Models

  • Baker's or brewer's yeast (Saccharomyces cerevisiae)

  • Bacterium (Escherichia con)

  • Fruit fly (Drosophila melanogaster)

  • Nematode (Caenorhabdiris elegans)

  • Zebrafish (Danio rerio)

  1. Plant Model

  • Arabidopsis thaliana

Non - Standard Model Organisms Currently Used in Experimental Biology

The diversity of species used in experimental biology is broad. If we worked with decapod crustaceans and can think of many species right away that people use for experimental biology, Procambarus fallax (Hagen 1870) f. Virginalis, Procambarus clarkii, Cancer borealis, Homarus americanus, Panulirus interruptus, fiddler crabs, mantis shrimp, and various hermit crabs.


At present, the "standard" model organisms that we listed out are in that position due to the reason NIH in the United States pushed hard on genetic research because of the project, named, Human Genome. As genetic techniques are getting cheaper, faster, and available more widely, there may be less incentive to stick with the genetic model organisms that are listed as the important ones.

FAQ (Frequently Asked Questions)

1. Mention any Single-Celled Organisms that have Eyes?

Ans. There are No such organisms with eyes. However, the single-celled organisms are sensitive to light. A single cell can perform all its work, such as making energy, finding fuel and oxygen, using the energy to find more fuel, and dividing it into another cell the same as itself.


Considering multicellular species, the starting cell for an individual is a single cell (the ovum in animals, the ovule in plants). After doubling its genetic material (fertilization), it makes itself into millions of body cells that will work for it.


These are known as the organs and include cells that will specialize in being sensitive to light - eyes. Eyes are the multicelled organs. Nevertheless, various single-celled organisms have "eyespots," which are paramecium and euglena.


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2. Explain About the Thale Cress type of Model Organism?

Ans. Thale cress, also called Arabidopsis thaliana, is a small flowering plant, and in plant biology, it is used widely as a model organism. Arabidopsis is also a member of the mustard (Brassicaceae) family, including cultivated species like radish and cabbage. Arabidopsis is not the major agronomic significance, but its ease of cultivation and small genome size offers essential advantages for basic research in molecular biology and genetics. Arabidopsis thaliana contains a genome size of about ~135 Mb and a haploid chromosome number of five.


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The Arabidopsis Information Resource (TAIR) has a database of molecular biology and genetic data for the model higher plant Arabidopsis thaliana. The data that is available from TAIR comprises complete genome sequence along with gene structure, gene expression, gene product information, DNA and seed stocks, genome maps, genetic and physical markers, information, and also the publications about the Arabidopsis research community. Every week, the gene product function data is updated from the latest community data submissions and published research literature.