What is called an organism and how does it differ from other objects in nature? Under this concept is understood a living body, which has a combination of various properties. They distinguish the body from inanimate matter. Translated from Latin, organismus means “I give a slender look”, “arrange”. This name itself implies a certain structure of any organism. This scientific category deals with biology. Living organisms are striking in their diversity. As separate individuals, they are part of species and populations. In other words, it is a structural unit of a certain standard of living. To understand what is called an organism, it should be considered from various aspects.
General classification
An organism, the definition of which quite fully explains its essence, consists of cells. Specialists distinguish such non-systematic categories of these objects:
• unicellular;
• multicellular.
In a separate group, such an intermediate category between them as colonies of unicellular organisms is distinguished. They are also divided in a general sense into nuclear and non-nuclear. For ease of study, all these objects are distributed in numerous groups. Thanks to this division into categories, living organisms (biology class 6) are summarized in an extensive biological classification system .
Cell concept
The definition of “organism” is inextricably linked with such a category as a cell. She is the basic unit of life. It is the cell that is the real carrier of all the properties of a living organism. In nature, only viruses that are non-cellular form do not have them in their structure. This elementary unit of vital activity and the structure of living organisms possesses the totality of properties and a metabolic mechanism. The cell is capable of independent existence, development and self-reproduction.
Many bacteria and protozoa, which are a single-celled organism, and multicellular fungi, plants, animals, consisting of many of these units of life, easily fit into the concept of a living organism. Different cells have their own structure. So, the structure of prokaryotes includes such organelles as a capsule, plasmalemma, cell wall, ribosomes, cytoplasm, plasmid, nucleoid, flagellum, drank. The following organelles are found in eukaryotes: nucleus, nuclear envelope, ribosomes, lysosomes, mitochondria, Golgi apparatus, vacuoles, vesicles, cell membrane.
The biological definition of “organism” is being studied by a whole section of this science. The structure and processes of their life is engaged in cytology. Recently, it is often called cell biology.
Unicellular organisms
The concept of "unicellular organism" implies an extra-systemic category of objects whose body has only one cell. It includes:
• Prokaryotes that do not have a formed cell nucleus and other internal organelles with membranes. They lack a nuclear envelope. They have an osmotrophic and autotrophic type of nutrition (photosynthesis and chemosynthesis).
• Eukaryotes, which are cells containing nuclei.
It is generally accepted that single-celled organisms became the first living objects on our planet. Scientists are sure that the most ancient of them were archaea and bacteria. Unicellular is also often called protists - eukaryotic organisms that are not included in the categories of fungi, plants and animals.
Multicellular organisms
A multicellular organism, the definition of which is closely related to the formation of a single whole, is much more complicated than unicellular objects. This process consists of the differentiation of various structures, which include cells, tissues and organs. The formation of a multicellular organism involves the separation and integration of various functions in ontogenesis (individual) and phylogenesis (historical development).
Multicellular organisms are composed of many cells, a significant part of which varies in structure and function. The only exceptions are stem cells (in animals) and cambium cells (in plants).
Multicellularity and Coloniality
In biology, multicellular organisms and single-cell colonies are distinguished. Despite some similarities between these living objects, there are fundamental differences between them:
• A multicellular organism is a community of many different cells that have their own structure and special functions. His body is made up of different tissues. Such an organism is characterized by a higher level of cell association. They are distinguished by their diversity.
• Unicellular colonies consist of the same cells. They are almost impossible to divide into tissues.
The border between colonialism and multicellularity is fuzzy. In nature, there are living organisms, for example, volvox, which in their structure are a colony of unicellular, but at the same time they have somatic and generative cells that differ from each other. It is believed that the first multicellular organisms appeared on our planet only 2.1 billion years ago.
Differences of organisms from inanimate bodies
The concept of "living organism" implies the complex chemical composition of such an object. It contains proteins and nucleic acids. In this he differs from the bodies of inanimate nature. They also differ in the totality of their properties. Despite the fact that bodies of inanimate nature also possess a number of physicochemical properties, the concept of "organism" includes more numerous characteristics. They are much more diverse.
To understand what is called an organism, it is necessary to study its properties. So he has the following characteristics:
• Metabolism, which includes nutrition (consumption of useful substances), excretion (removal of harmful and unnecessary products), movement (changing the position of the body or its parts in space).
• Perception and processing of information, which includes irritability and excitability, allowing you to perceive external and internal signals and selectively respond to them.
• Inheritance, which allows transmitting its traits to descendants and variability, which is the difference between individuals of the same species.
• Development (irreversible changes throughout life), growth (weight and size increase due to biosynthesis processes), reproduction (reproduction of oneself).
Cell Based Classification
Specialists divide all forms of living organisms into 2 suprasternies:
• Nuclear (prokaryotes) - evolutionarily primary, the simplest type of cells. It was they who became the first forms of living organisms on Earth.
• Nuclear (eukaryotes) originating from prokaryotes. This more progressive type of cell has a nucleus. Most living organisms on our planet, including humans, are eukaryotic.
The nuclear overpowerment, in turn, is divided into 4 kingdoms:
• protists (paraphilitic group), which are ancestral to all other living organisms;
• mushrooms;
• plants;
• animals.
Prokaryotes include:
• bacteria, including cyanobacteria (blue-green algae);
• archaea.
The characteristic features of these organisms are:
• lack of a designed core;
• the presence of flagella, vacuoles, plasmids;
• the presence of structures in which photosynthesis is carried out;
• form of reproduction;
• the size of the ribosome.
Despite the fact that all organisms differ in the number of cells and their specialization, all eukaryotes are characterized by a certain similarity in the structure of the cell. They differ in common origin, therefore this group is a monophyletic taxon of the highest rank. According to scientists, eukaryotic organisms appeared on earth about 2 million years ago. An important role in their appearance was played by symbiogenesis, which is a symbiosis between a cell with a nucleus capable of phagocytosis and bacteria absorbed by it. They became the precursors of such important organelles as chloroplasts and mitochondria.
Mesocaryotes
In nature, there are living organisms, which are an intermediate link between prokaryotes and eukaryotes. They are called mesocaryotes. They differ from them in the organization of the genetic apparatus. Dinoflagellates (dinophytes) belong to this group of organisms. They have a differentiated nucleus, but the primitive features that are inherent in the nucleoid have been preserved in the cell structure. The type of organization of the genetic apparatus of these organisms is considered not only as a transitional, but also as an independent branch of development.
Microorganisms
Microorganisms are a group of living objects of extremely small size. They cannot be seen with the naked eye. Most often, their size is less than 0.1 mm. This group includes:
• nuclear-free prokaryotes (archaea and bacteria);
• eukaryotes (protists, fungi).
The vast majority of microorganisms are a single cell. Despite this, in nature there are unicellular organisms that can be easily seen without a microscope, for example, the giant polycarion Thiomargarita namibiensis (marine gram-negative bacterium). Microbiology studies the life of such organisms.
Transgenic organisms
Recently, a phrase such as a transgenic organism has been increasingly heard. What is it? It is an organism into the genome of which the gene of another living object is artificially introduced. It is introduced in the form of a genetic construct, which is a DNA sequence. Most often, it is a bacterial plasmid. Thanks to such manipulations, scientists get living organisms with qualitatively new properties. Their cells produce a gene protein that has been introduced into the genome.
The concept of "human body"
Like any other living objects of people, biology studies science. The human body is a holistic, historical, dynamic system. It has a special structure and development. Moreover, the human body is in constant communication with the environment. Like all living objects on Earth, it has a cellular structure. They form tissue:
• Epithelial, located on the surface of the body. It forms the skin and lines the walls of hollow organs and blood vessels from the inside. Also, these tissues are present in closed cavities of the body. There are several types of epithelium: cutaneous, renal, intestinal, respiratory. The cells that form this tissue are the basis of such modified structures as nails, hair, tooth enamel.
• Muscular, with the properties of contractility and excitability. Thanks to this tissue, motor processes are carried out within the body itself and its movement in space. Muscles are made up of cells that contain microfibrils (contractile fibers). They are divided into smooth and striated muscles.
• Connective, which includes bone, cartilage, adipose tissue, as well as blood, lymph, ligaments and tendons. All its varieties have a common mesodermal origin, although each of them has its own functions and structural features.
• Nervous, which is formed by special cells - neurons (structurally functional unit) and neuroglia. They differ in their structure. So the neuron consists of a body and 2 processes: branching short dendrites and long axons. Coated, they make up nerve fibers. Functionally, neurons are divided into motor (efferent), sensory (afferent), and intercalary. The place of transition from one of them to another is called a synapse. The main properties of this tissue: conductivity and excitability.
What is called the human body in a broader sense? Four types of tissues form organs (part of the body with a certain shape, structure and function) and their systems. How are they formed? Since one body cannot cope with the performance of certain functions, their complexes are formed. What are they? Such a system is a combination of several organs that have a similar structure, development and function. All of them form the basis of the human body. These include the following systems:
• musculoskeletal (skeleton, muscles);
• digestive (glands and tract);
• respiratory (lungs, airways);
• sensory organs (ears, eyes, nose, mouth, vestibular apparatus, skin);
• genital (female and male genital organs);
• nervous (central, peripheral);
• circulatory (heart, blood vessels);
• endocrine (endocrine glands);
• integumentary (skin);
• urinary (kidneys leading the way).
The human body, the definition of which can be represented as a combination of various organs and their systems, has the main (determining) beginning - the genotype. It represents a genetic constitution. In other words, it is a collection of genes of a living object received from parents. Any kind of microorganism, plant, animal has a characteristic genotype.