Definition of Model Organism
A model organism is a non-human species that has been extensively studied and is easy to maintain and reproduce in a laboratory setting, as well as having specific experimental benefits.
Non-human species are kept in laboratories as model creatures to study and experiment with biological processes. Model organisms are used to learn more about other, more difficult-to-understand species. Model organisms have the following characteristics:
Maturity occurs quickly.
Simple to work with
Life expectancy is limited.
Capacity to produce a big number of children
Understanding the progression of disease in humans, for example, could take a long period. A model organism, on the other hand, has the ability to develop a disease and its symptoms quickly. This aids scientists in quickly learning and comprehending the condition. As a result, model organisms aid in the investigation of the causes of newly created diseases. Model organisms have evolved into critical instruments in therapeutic research.
Advantages of Using Model Organisms in Genetics Research
Many model organisms have the ability to reproduce in vast numbers.
Some have an extremely short generation time, or the time between birth and the ability to reproduce, allowing multiple generations to be observed at the same time.
Mutants allow scientists to investigate certain traits or diseases. These are model organisms that have had a change or mutation in their DNA, which may have resulted in a change in a characteristic.
Some model organisms contain genes or genomes that are similar to humans.
To build highly detailed genetic maps, model organisms might be used:
Genetic maps are a visual representation of the position of distinct genes on a chromosome, similar to a real map but with major landmarks in the genome.
For example, SNPs (single nucleotide polymorphisms) or genes that differ amongst individuals of the same species.
Imaging Model Organisms: Challenges
Model organism research is extremely diverse, and the challenges of using microscopy techniques vary depending on whether they are used for dynamic studies or the study of molecular events, as well as the complexity of the model organism used, which can range from a few cells in C elegans to large complex animals like the mouse.
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 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 being born - of about ten weeks. Adult mice often reproduce every three weeks and because the scientists simultaneously can observe different generations of mice at a time.
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.
Yeast (Saccharomyces Cerevisiae)
Yeast is the simplest eukaryotic organism 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.
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.
The Worm (Caenorhabditis Elegans)
Caenorhabditis elegans, the worm, has been extensively used as the model organism since the 1970s when 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.
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.
Mammalian Models
Rat (Rams norvegicus)
Mouse (Mus muscu/us)
Non - Mammalian Models
Baker's or brewer's yeast (Saccharomyces cerevisiae)
Bacterium (Escherichia con)
Fruit fly (Drosophila melanogaster)
Nematode (Caenorhabdiris elegans)
Zebrafish (Danio rerio)
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.
FAQs on Model Organism– Definition, Types, Characteristics and FAQs
1. What is a model organism in biology?
A model organism is a non-human species that is extensively studied to understand specific biological phenomena. These organisms are chosen because their biological processes, such as genetics, development, or disease progression, are expected to provide insights into the workings of other, more complex species, including humans.
2. What are the key characteristics of a good model organism?
An ideal model organism possesses several key characteristics that make it suitable for laboratory research. These include:
- A short generation time and rapid life cycle.
- The ability to produce a large number of offspring.
- Being easy and inexpensive to maintain and grow in a lab setting.
- A small genome that is relatively easy to sequence and manipulate.
- Possessing biological traits or disease models that are analogous to humans.
3. Why do scientists use model organisms instead of studying humans directly?
Scientists use model organisms for several crucial reasons where direct human study is impractical or unethical. They allow for the investigation of biological processes over multiple generations in a short time frame. Researchers can also perform genetic manipulations and controlled experiments on model organisms to understand gene function or disease pathways, which cannot be done on humans.
4. What are some common examples of model organisms used in research?
Some of the most widely used model organisms in biological research include:
- The bacterium Escherichia coli (E. coli) for studying basic genetics and metabolism.
- The yeast Saccharomyces cerevisiae for understanding eukaryotic cell biology.
- The fruit fly Drosophila melanogaster for genetics and developmental biology.
- The nematode worm Caenorhabditis elegans (C. elegans) for studying cell death and development.
- The zebrafish Danio rerio for vertebrate development and disease modelling.
- The house mouse Mus musculus as a mammalian model for human diseases.
5. Why is the fruit fly, Drosophila melanogaster, so important in the study of genetics?
The fruit fly, Drosophila melanogaster, is a cornerstone of genetics because its large chromosomes and rapid life cycle made it ideal for early studies. Thomas Hunt Morgan's work with fruit flies provided the first concrete evidence that genes are located on chromosomes. Its simple genetics, with only four pairs of chromosomes, and the vast number of available mutants continue to make it invaluable for studying heredity and gene function.
6. How do model organisms like zebrafish help in studying human diseases?
Zebrafish (Danio rerio) are powerful models for studying human diseases because they share approximately 70% of their genes with humans. Their embryos are transparent and develop externally, allowing scientists to directly observe organ development and the progression of diseases like cancer or cardiovascular disorders in a living vertebrate. This makes them excellent for testing potential drugs and understanding disease mechanisms at a cellular level.
7. What is the main difference between a mammalian and a non-mammalian model organism?
The main difference lies in their physiological and genetic proximity to humans. Mammalian models, like the mouse (Mus musculus), share a more recent common ancestor with humans, making their immune, endocrine, and nervous systems highly comparable. Non-mammalian models, like the fruit fly or yeast, are simpler and easier to manipulate for studying fundamental cellular processes that are conserved across all eukaryotes, but may lack complex organ systems found in mammals.
8. How have model organisms contributed to major discoveries like the Human Genome Project?
Model organisms were foundational to the success of the Human Genome Project. The genomes of simpler organisms like E. coli, yeast, and C. elegans were sequenced first. This allowed scientists to develop and refine the DNA sequencing technologies and bioinformatics tools needed for a project as massive as the human genome. Furthermore, comparing the human genome to these model organisms helps identify genes and understand their functions, a field known as comparative genomics.
