What is an organism?
In biology, an organism or living being is a singular and differentiated individual made up of several hierarchical and specialized organic matter. It consists of biochemical transmission and communication systems that enable it to maintain its inner balance and at the same time exchange matter and energy with the environment around it. In other words, an organism is a living being that can nourish, grow, reproduce, and die.
All known organisms except for viruses are made up of cells and have a metabolism that enables them to guarantee their existence and trigger their biological processes in exchange for energy exchange with the environment. The ultimate goal of any organism seems to be a reproduction, that is, the maintenance of its species and the transmission of its genetic material (heredity).
From a chemical point of view, living beings differ from the nature that surrounds them in their almost exclusive composition based on carbon, hydrogen, oxygen, and nitrogen, that is, based on organic molecules that differ greatly from the inorganic molecules of inert matter.
Organisms are classified according to various criteria. The main criterion is a physical and physiological similarity, and they belong to a determined revolutionary group that shares a common ancestor (a taxon). According to this criterion, living beings can belong to five different realms of life, which in turn are divided into two different areas or superkingdoms:
- Prokaryote domain. In this domain are the most primitive known organisms, all unicellular and devoid of a cell nucleus, that is, with circular, simple, and loose DNA molecules in the cell cytoplasm. They are the oldest living beings evolutionarily and the simplest and smallest. Two kingdoms are identified in this domain:
- Bacteria kingdom. In this kingdom are the most abundant prokaryotes on the planet, bacteria, adapted to almost all habitats and to various models of life-based on photosynthetic, chemosynthetic, parasitic metabolisms, etc.
- Archaea kingdom. Archaebacteria or archaea gained their reputation as a separate kingdom in relatively recent times when it was discovered that they possess metabolic pathways and biochemical characteristics more similar to those of eukaryotes. They are usually adapted to very demanding environments with life, such as extreme niches such as salt flats, hot springs, etc. Depending on the classification used, archaea can constitute, like bacteria, an individual domain.
- Eukaryota domain. The second domain of life is made up of unicellular and multicellular organisms whose cells, of greater size and complexity, are equipped with a cell nucleus in which DNA resides, in the shape of a double helix, as well as other similar organelles. They are an evolutionary step forward concerning prokaryotes and, thanks to this, they allowed the existence of multicellular beings. In this domain four kingdoms are identified:
- Protist kingdom. Protists are eukaryotic unicellular organisms, which would become the link between prokaryotes and multicellular organisms. In this kingdom there are various types of living beings, both autotrophic and heterotrophic, that is, that photosynthesize or that feed on other living beings, including parasites that cause disease.
- Kingdom Plantae. This is the kingdom of plants, that is, multicellular organisms (except for some algae) that carry out photosynthesis: the transformation of CO2 and solar energy into starches that serve for the growth and maintenance of the organism. For this, they are endowed with chlorophyll, a pigment that gives them their characteristic green color.
- Fungi kingdom. The kingdom of fungi, which share cellular characteristics with plants (such as the presence of the cell wall, but of chitin instead of cellulose) and with animals (such as their heterotrophic nutrition, from decomposing organic matter ). Except for unicellular yeasts, they are always multicellular and reproduce through spores.
- Animalia kingdom. The kingdom of animals, the only living beings endowed with voluntary mobility, in its enormous diversity, from insects, worms and snails, to amphibians, reptiles, birds, and mammals. Animals reproduce sexually and their metabolisms operate based on the oxidation of glucose, for which they must breathe oxygen from air or water (using lungs or gills).
Autotrophic and heterotrophic organism
An important and common distinction between all types of living beings is the distinction between living beings that can synthesize their nutrients (autotrophs) and those that are unable to do so and the organic matter of other living beings (heterotrophs) need to consume…
Among the living beings of the first type, we find plants and those microorganisms that can chemically synthesize their nutrients under extreme environmental conditions (chemosynthesis). These organisms are known as producers in their respective ecosystems and are usually located at the base of the food pyramid.
However, the living beings of heterotrophic metabolism are the most diverse and make different trophic levels over the producer. In the first stage are those herbivores who get their raw material from the consumption of plants, fruits, or derivatives. The second tier consists of predators that feed on generally small herbivores. And finally, on the third level, the big predators that feed on other predators and herbivores are the end of the chain.
After all, decomposing organisms (such as fungi, insects, scavengers, and bacteria) are also heterotrophs that serve to break down organic residues and act as nature’s recycling department.
The human organism is the only one of a known nature that has a full self-awareness and intelligence that enables it to change the environment in its favor rather than adapting to the challenges of the environment. Humans are the product of billions of years of continuous evolution from which the first Homo sapiens emerged about 2 million years ago.
Our body is multicellular (it consists of almost 100 trillion cells) and is made up of 50% water. We are mammals, bipeds, bilaterally symmetrical creatures, and vertebrates with oxygen-dependent metabolism (breathing) and glucose, which we take in from an omnivorous diet.
Examples of organism
Every living being on the planet is a perfect example of an organism or living being. These include plants such as algae, ferns, fruit trees or shrubs in the plains, and cacti in the desert. also, the mushrooms we see on the forest floor or the roots of trees (mycorrhizae), or those that are so annoying that athletes suffer between their toes; also animals of all kinds, marine, terrestrial, and flying, humans themselves, and the bacterial flora that make life in our intestines in a symbiotic relationship with our organism. Wherever there is life, we can identify an organism.
What is an organism? Types, Examples, Autotrophic and Heterotrophic