We explain what life is and what the smallest unit in a living being is. In addition, its levels of organization and general characteristics.
What is life?
From biology, it has classically been defined as A living being is one that is capable of being born, developing, reproducing and dying.; so that life would be understood as the set of those capacities. Human life, however, is often seen as a broader concept, with highly complex philosophical components.
Almost all living things They increase in size over timea phenomenon called growth. At the same time, more or less profound and evident changes occur over time, which we will analyze later.
On the other hand, Living beings need energy to carry out their vital functions.This energy can come from the sun in the form of photons, or it can come from the degradation of nutrients contained in food.
See also: Microorganisms.
Characteristics of life:
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Minimum unit: the cell
It is accepted that The smallest unit of organization in a living being is the cellalthough it is clear that there are important subcellular structures. This feature was intensely debated after the discovery of viruses, parasites consisting of just one molecule of deoxyribonucleic acid or ribonucleic acid surrounded by a protein cap.
More in: Cell.
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Different levels of organization
Life can be presented with a very basic level of organizationas is the case, for example, with bacteria (unicellular beings that reproduce by simple binary fission), up to high levels of complexity, with the presence of different types of tissues, especially suited to performing specific functions.
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Different structures
In the life very diverse structures may be involvedFor example, a higher animal has organs in addition to tissues; a plant does too. An insect appears in the form of a larva and then as an adult, which are completely different from each other.
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Growth and development
Almost all living things increase in size over time, a phenomenon called growth. In turn, more or less profound changes are taking place and are evident throughout this time; often these changes are related to sexual maturity, this is called development. The metamorphosis experienced by insects is a paradigmatic case of vital development.
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Energy
Every living being needs to obtain energy to carry out its vital functions. That energy can come from the sun in the form of photonsor it may come from the degradation of nutrients contained in food.
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Depends on metabolism
So that nutrients can be useful in terms of energy and as chemical skeletons, In every living being there must be processing molecules or enzymes.which ensure the biochemical processing that leads to the permanent degradation and synthesis of compounds.
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Involves adaptation phenomena
Through millions of years of evolution, living beings they adapted to the environments in which they had to live and the availability of food.
A classic example is the giraffe, an animal that with its long necks can reach the canopy of leaves of taller trees, from which it feeds. Another example is that of cacti that grow in desert areaswhich thanks to the thick cover that its leaves have, prevents too much water from being lost.
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Irritability or excitability
This phenomenon refers to the ability to react to certain stimuli. For example, pollinating insects are attracted to the colors of the flowers, sunflowers orient their flowers following the path of the sun; Sneezing is often a reaction to a respiratory poison.
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It perpetuates itself
Every form of life has at least one mechanism of reproduction and perpetuation, some have more than one. Mechanisms are usually classified as sexual or asexual.depending on whether or not there is a combination of gametes and therefore genetic material.
You may be interested in: Genetic code.
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Genetic and environmental factors
Life depends on the information contained in the geneswhich is inherited from generation to generation, but also from the restrictions imposed by the surrounding environment, and this is generally the basis of evolution.