What is an organism called and how does it differ from other objects in nature? This concept is understood as a living body, which has a combination of various properties. It is they who distinguish the organism from inanimate matter. Translated from Latin, organismus means “I communicate a slender appearance”, “I arrange”. The name itself implies a certain structure of any organism. Biology deals with this scientific category. Living organisms amaze with their diversity. As 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, one should consider it from different 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 non-nuclear andnuclear. For ease of study, all these objects are divided into numerous groups. Thanks to this division into categories, living organisms (biology grade 6) are summarized in an extensive biological classification system.
Cage concept
The definition of the concept of "organism" is inextricably linked with such a category as a cell. It 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 structure of living organisms has the whole set of properties and the mechanism of metabolism. The cell is capable of independent existence, development and self-reproduction.
The concept of a living organism easily fits many bacteria and protozoa, which are a single-celled organism, and multicellular fungi, plants, animals, consisting of many of these life units. Different cells have their own structure. Thus, the composition of prokaryotes includes such organelles as a capsule, plasmalemma, cell wall, ribosomes, cytoplasm, plasmid, nucleoid, flagellum, pili. Eukaryotes have the following organelles: nucleus, nuclear envelope, ribosomes, lysosomes, mitochondria, Golgi apparatus, vacuoles, vesicles, cell membrane.
The biological definition of "organism" studies a whole section of this science. Cytology deals with the structure and processes of their vital activity. More recently, it has been more commonly referred to as cell biology.
Single-celled organisms
The concept of "unicellular organism" implies a non-systemic category of objects whose body has only one cell. These include:
• 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 that contain nuclei.
It is generally accepted that unicellular organisms were the first living objects on our planet. Scientists are sure that the most ancient of them were archaea and bacteria. Protists are also often called unicellular - 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 includes the separation and integration of different functions in ontogenesis (individual) and phylogenesis (historical development).
Multicellular organisms consist of many cells, many of which differ in structure and function. The only exceptions are stem cells (in animals) and cambial cells (in plants).
Multicellularity and coloniality
In biology, there are multicellular organisms andunicellular colonies. Despite some similarity of 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 integration. They are distinguished by their diversity.
• Colonies of unicellular organisms consist of identical cells. They are almost impossible to separate into fabrics.
The boundary between coloniality and multicellularity is fuzzy. In nature, there are living organisms, for example, volvox, which in their structure are a colony of unicellular organisms, but at the same time they contain 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 between organisms and inanimate bodies
The concept of "living organism" implies the complex chemical composition of such an object. It contains proteins and nucleic acids. This is what distinguishes it from the bodies of inanimate nature. They also differ in the totality of their properties. Despite the fact that bodies of inanimate nature also have a number of physical and chemical 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 it has the following characteristics:
• Metabolism, which includes nutrition (consumption of usefulsubstances), excretion (removal of harmful and unnecessary products), movement (change of 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.
• Heredity, which allows you to transfer your traits to descendants and variability, which is the differences between individuals of the same species.
• Development (irreversible changes throughout life), growth (increase in weight and size due to biosynthetic processes), reproduction (reproduction of others like themselves).
Classification based on cell structure
Specialists divide all forms of living organisms into 2 kingdoms:
• Pre-nuclear (prokaryotes) - evolutionarily primary, the simplest type of cells. It was they who became the first forms of living organisms on Earth.
• Nuclear (eukaryotes) derived from prokaryotes. This more advanced cell type has a nucleus. Most living organisms on our planet, including humans, are eukaryotic.
The nuclear kingdom, in turn, is divided into 4 kingdoms:
• protists (paraphyletic group), which are ancestral to all other living organisms;
• mushrooms;
• plants;
• animals.
Prokaryotes include:
• bacteria, including cyanobacteria (blue-green algae);
• archaea.
Characteristic features of these organismsare:
• no formal core;
• the presence of flagella, vacuoles, plasmids;
• the presence of structures in which photosynthesis takes place;
• breeding form;
• Ribosome size.
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, so 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 that has a nucleus and is capable of phagocytosis, and the bacteria absorbed by it. It was they who became the precursors of such important organelles as chloroplasts and mitochondria.
Mesokaryotes
In nature, there are living organisms that are an intermediate link between prokaryotes and eukaryotes. They are called mesokaryotes. They differ from them in the organization of the genetic apparatus. This group of organisms includes dinoflagellates (dinophyte algae). They have a differentiated nucleus, but the cell structure retains the primitive features that are inherent in the nucleoid. 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. Themimpossible to see with the naked eye. Most often, their size is less than 0.1 mm. This group includes:
• non-nuclear prokaryotes (archaea and bacteria);
• eukaryotes (protists, fungi).
The vast majority of microorganisms are a single cell. Despite this, there are unicellular organisms in nature that can be easily seen even without a microscope, for example, the giant polykaryon Thiomargarita namibiensis (marine gram-negative bacterium). Microbiology studies the life of such organisms.
Transgenic organisms
Recently, such a phrase 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 obtain 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, the science of biology studies. The human body is a holistic, historically developed, 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 tissues:
• Epithelial, located onbody surface. It forms the skin and lines the walls of hollow organs and blood vessels from the inside. Also, these tissues are present in closed body cavities. There are several types of epithelium: skin, kidney, 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 (structural and 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. Covered with sheaths, they make up nerve fibers. Functionally, neurons are divided into motor (efferent), sensitive (afferent), intercalary. The place of transition from one of them to another is called a synapse. The main properties of this tissue are conductivity and excitability.
What is called the human body in a broader sense? Four types of fabricsform organs (part of the body with a certain shape, structure and function) and their systems. How are they formed? Since one organ cannot cope with the performance of some functions, their complexes are formed. What are they? Such a system is a collection of several organs that have a similar structure, development and functions. 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);
• sense organs (ears, eyes, nose, mouth, vestibular apparatus, skin);
• sexual (female and male reproductive organs);
• nervous (central, peripheral);
• circulatory (heart, blood vessels);
• endocrine (endocrine glands);
• integumentary (skin);
• urinary (kidneys that excrete pathways).
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 is the genetic constitution. In other words, it is a set of genes of a living object received from parents. Any kind of microorganisms, plants, animals has a characteristic genotype.
