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Organism Definition

An organism is a living being which owns organized body structures, which usually act to stimulate, reproduce, develop, can carry, and also keep up homeostasis. We can say that the organism can be anything such as animals, plants, fungus, bacteria, or even archaeon which lives on the globe. These organisms may be divided into different ways. One of these ways is dependent on the amount number of cells which make it up. There are two major classifications in this regard, Single-celled which owns only one cell (for example bacteria, etc) and the second one is multicellular which owns various cells (for example animals, humans, as well as plants).

Organism Definition

But that is not only a way to classify the organization, it can also be classified with the help of their subcellular structures. Some of them have well-defined nuclei, also known as eukaryotes and those who don't have well-defined nuclei are known as prokaryotes.

One most common thing about both is that they both own the same genetic material but the locations can be completely different. In all eukaryotes, the genetic items are found inside the nucleus but in the Prokaryotes there is a specific region which is known as nucleoid and contains genetic material.

There are no specific rules as a Unicellular can be any prokaryote or even a eukaryote. Most of the Prokaryotes are shown by two different domains - Bacteria as well as Archeae. In the Eukaryotic organisms cell nuclei or additional membranes are called organelles. And this is why there are various organisms such as Fungi, Animals and plants are a few examples of such kingdoms of organisms which are eukaryotes.

In the modern system, the classification of these living things is into three different domains:

  1. Archaea (archaebacteria)
  2. Bacteria (eubacteria)
  3. Eucarya (eukaryotes)

As already mentioned bacteria and Archaea are known as examples of Prokaryotic organisms but the Eukarya, which as per the name says have a number of Eukaryotes. The part of science which has a brief study of all living beings is known as Biology. In this field of biology, there is all the knowledge about what is the structure, how it works, and what is distribution and evolution of all living beings.

As per the records and all the research says, there is a huge number of different species which can be between 2 million to almost 1 trillion and there is an estimation that in all total, till now only 1.7 million is defined and found.

Much more than 99% of all these species, almost 5 billion species that ever existed and a huge number is finished.

As per the reports, a set of 355 genes from the LUCA of all ever-exciting organisms were identified.

Organism Definition

The best definition of an organism is defined as a very important entity that exhibits life. Everything that exists no matter if it is living or non-living is made up of molecules. Although the structure and the characteristics are completely different from each other and can be differentiated from it. As for the example, we can say that any organism is created by one or even more than one cell.

So all organisms can be remembered as a structure that is created with the help of molecules and can create other living beings. They are also born with the help of nature with the help of molecules. These molecules are known as biomolecules and examples of them are proteins, nucleic acids, calcium, etc. These biomolecules are very essential and play an important role in maintaining all the major complex molecules, and thus can create subcellular structures. These structures are all kept in a cell. So It is essential that cells are the most basic and important biological entity which is necessary for any living thing and no living being can live without at least one cell.

Also, there is one more very important element of these cells which is known as the chromosome. As the chromosome takes care of the genetic material and plays different roles in all living beings, as in bacteria, and archaea, this chromosome is an important circular strand of the DNA. But in humans and bigger organisms, the DNA has a completely different linear strand.

There is a specific part of DNA that plays a major role in all the physical as well as heredity characteristics of an organism known as the genes. Genes work with the help of amino acids, proteins, and molecules of RNA. Proteins are very important and ubiquitous units of all biomolecules. Various Enzymes are important for different biological processes and to maintain the correct workflow of an organism's body.

There is a chance that the genes may go through changes and such various changes can also cause other mutations. These mutations may sometimes cause novel features. On the other hand, sometimes it may also be lethal and create detrimental changes but it has been observed that mutations sometimes bring very positive and good change with profitable results.

In some organisms, Mutation can be reasoned by evolution as well as natural choices. But in the end, all these mutations are part of survival and are necessary for all living beings. For instance, take an example of a bacteria, in which strains were primarily supposed to transform antibiotics and work as resistance to other antibiotics while developing new genes. So, thus we can come to the conclusion that any organism can easily adapt to new changes and can change at any time without affecting life much.

Apart from these enzymes, there are also different biological processes that may require energy. The best example of such a process is ATP, which in various living beings may be utilized as the most important part of all the biological changes.

In every plant or different organisms with photosynthetic abilities, light energy is essential for converting chemical energy with the help of the photosynthesis procedure. Another very popular method of the production of energy is with the help of cellular respiration. Cellular respiration is a very important cellular method in which carbohydrates are used to create new chemical energies.


The organisms are made up of a few compounds which are divided into smaller molecules, macromolecules, and further other molecules. Macromolecules are divided into four major categories which are nucleic acid, protein, carbohydrates, and lipids. Nucleic acids such as DNA keep genetic data as a line of nucleotides. The most popular sequence of four various kinds of nucleotides such as Adenine, cytosine, Guanine, and thymine may describe various characteristics that create the organisms. These sequence lines may also be divided up into codons, every part of such a sequence of three nucleotides is correlated into a specific amino acid. So, a line of DNA codes for a specific protein which is because of the chemical properties of the amino acids which it is made from, folds in a specific manner and so does a specific function. These protein functions which might have known as:

  1. Enzymes, that cause the reactions of metabolism
  2. Tubulin or collagen are a few examples of structural protein
  3. There are few regulatory proteins, like transcription factors or cyclins, that help in regulating the cell cycle.
  4. Signaling molecules or even their receptors, like a few hormones and their receptors
  5. There are a few proteins that are defensive proteins that might have everything from antibodies of the immune system to toxins, for example, dendrotoxins of snakes, to proteins that might also have unusual amino acids like canavanine.

A bilayer of various phospholipids also makes up the membrane of cells which is a barrier, holding everything within a cell and ignoring compounds from freely passing into, and out of the cell. Because of the selective permeability of the membrane, few specific compounds can actually go through it.


Viruses are usually not counted within the categories of Organisms as they do not have the quality of self-reproduction, can't grow themselves, and also don't have metabolism. Anyhow some organisms are also not able to survive on their own and thus needed to survive as obligate intracellular parasites, they are also able in doing independent metabolism and also procreation. But as few viruses own a small number of enzymes and molecules that add characteristics of living beings, still as they do not have any individual metabolism, they also cant synthesize and can not create such organic compounds which are essential to their origin. According to Nature, this is not how any organism reproduces, so thus their existence is completely dependent on the workflow of the Host cell, which makes them common just like any other non-living being. The only reason which makes this theory incorrect is that as Viruses consist of their own genes, and can easily evolve, they are capable of surviving and should be considered as living organisms. This topic has been discussed for years as a number of Scientists always said that due to the disability of self-reproduction, the viruses can not evolve and this is why they need to co-evolve with their host cells and can't do anything on their own. If there was no such host cell, there was no virus. Anyways, this is not the same story in the case of cells, even if there were no viruses, from a different direction, a cell still was capable of evolution and did not rely on any virus. Also, the fact that the viruses need hosts to replicate for the reproductions, makes them completely dependent on the cells. The first ever discovery of such viruses with their genes was done with the help of gene coding of the energy metabolism and with the help of protein synthesis gave rise to this argument of whether they are living beings or not an organism. It has been believed that due to the genes in them, these viruses were once also able to metabolize but later lost the ability. Anyhow, after some time with the help of genes coding the energy and protein metabolism, it was clear that they have such cellular origin and thus these genes took place due from the viral hosts with the help of horizontal gene transfers.


All the Organisms can be metabolized. So it simply can be understood by the process which carries out to keep it alive. Metabolic procedures also consist of growth, reproduction, results to stimuli, elimination of wastes, and biosynthesis. Two types of metabolism are anabolism and catabolism. Anabolism is a type in which it consists of energy-needed reactions which can also bring you to the Building up of biomolecules. On the other hand, catabolism consists of procedures that break down particles into much simpler molecules. Living beings can bring out these metabolic procedures in orchestrated, systematic methods. They also have various regulatory mechanisms to make sure that homeostasis situations are trustable and can be kept.

Organisms are also able to find and react to stimuli. They can find changes in the environment. Bigger animals and humans are blessed with the ability to detect such stimuli with the help of five major senses, which are eyesight, smell, touch, taste, and also the ability to hear. These senses play a really important role in survival. For example, a human uses eyes to see and survive in the dark.


Organisms also have the ability to give birth. They can also raise these small creatures until they can survive on their own. Reproduction can be done in two ways which are sexual (with the involvement of gametes) as well as asexual reproduction (with no involvement of gametes).

Mostly all eukaryotes, are reproduced by sexual reproductions and are likely to pass within the generations. According to the reports, the core set of genes for meiosis in the descendants diverged primarily from the eukaryotic evolutionary tree. Experts believe that the eukaryotes were also the ones who didn't have sexual reproduction from the start. But few of them like Amoeba still at that time used to do it.

Things are completely different in prokaryotes, where NBT (natural Bacterial Transformation) consists of DNA from a bacterium to another integration of the donor DNA in which the recipient chromosome by the process of recombination. NBT is also believed to be the earliest sexual process and may have occurred in both Bacteria as well as Archaea which are also studied under the bacteria category. This change is also under bacterial adaptation and is never done by any accident occurrence, as it is completely based on the number of genes that especially interact with each other to begin a new state of natural competence to do such a complex procedure. And thus this transformation is the most common way of DNA transfer in the prokaryotes.

Cloning and Synthetic Organisms

As the new world is changing a lot and thus Modern Biotechnologies are also becoming much more updated and changing. Now they want to keep challenging the traditional approaches to the organism and all living species. So they keep trying Cloning which is a modern method of developing a new and multicellular organism. There is a chance that these new organisms may look like some other creature but have the potential and characteristics of their own or sometimes of other creatures which makes them completely new species of organisms. Thus we can also say that this procedure of cloning is a topic of ethical debate as many are in favor but most are not.

This process started when in 2008, a team of scientists from the J. Craig Venter Institute went successful in collecting a synthetic bacterial genome known as the Mycoplasma genitalium, with the help of yeast in 25 different overlapping DNAs Fragments within a step. With the use of such yeast recombination it in a very good manner simplifies the complex process of assembling DNAs from both the synthetic as well as the natural fragments. There were also further companies like Synthetic Genomics which took advantage of further commercial utilizations of such custom-designed genomes and created other organisms.

Organisms and Chemistry

It is a major fact that organisms work with the help of really complex chemical systems, which are done in such a manner that supports the reproduction and various measures of survival and reliability. The same rules help in non-living chemistry that owns the chemical procedure of life. It is mainly the phenomena of whole organisms which determine their fitness to an environment and also results in the survival of their DNA-based genes.

They very clearly have their own origin, metabolism, and further other internal features to all chemical phenomena, mainly the chemistry of larger natural molecules. Organisms are very complex systems of chemical compounds that through interactions and atmosphere and play a major role in survival.

Organisms are mostly half-closed chemical systems. Even if they are single units of living beings as per the requirement of definitions that are not closed to the people around them. To keep working, they always need to keep taking and releasing energy. Autotrophs help in producing usable energy in the form of natural compounds with the help of light from the sun or other non-organic compounds, whereas heterotrophs include the organic compounds for the atmosphere. The basic chemical element of these compounds is Carbon. These elements own the chemical properties which are great affinity for connecting bonds with further small atoms and also the chemical atoms and have a very less size making them able to form different multiple bonds, which also makes them perfect as the basic entity of healthy life. It is also capable of developing three small atoms like CO2, also large chains of different thousands of atoms that can also keep data such as Nucleic acids and keep the cell all together and transform information like proteins.

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