Animal cell structure with symbols. Structural units of all tissues and organs of the cell

The cell - the smallest structure of the entire plant and animal world - is the most mysterious phenomenon of nature. Even at its own level, the cell is extremely complex and contains many structures that perform specific functions. In the body, a combination of certain cells forms tissues, tissues - organs, and those - organ systems. The structure of the animal is similar in many respects, but at the same time it has fundamental differences. For example, the chemical composition of cells is similar, the principles of structure and life activity are similar, but there are no centrioles in plant cells (except for algae), and starch serves as a nutritional reserve base.

The animal is based on three main components - the nucleus, cytoplasm and cell wall. Together with the nucleus, the cytoplasm forms protoplasm. The cell membrane is a biological membrane (partition) that separates the cell from the external environment, serves as a shell for cell organelles and the nucleus, and forms cytoplasmic compartments. If you place the preparation under a microscope, then the structure of the animal cell can be easily seen. The cell wall contains three layers. The outer and inner layers are protein, and the intermediate layer is lipid. In this case, the lipid layer is divided into two more layers - a layer of hydrophobic molecules and a layer of hydrophilic molecules, which are arranged in a certain order. On the surface of the cell membrane is a special structure - the glycocalyx, which provides the selective ability of the membrane. The shell passes the necessary substances and delays those that are harmful. The structure of the animal cell is aimed at providing a protective function already at this level. The penetration of substances through the membrane occurs with the direct participation of the cytoplasmic membrane. The surface of this membrane is quite significant due to bends, outgrowths, folds and villi. The cytoplasmic membrane passes both the smallest particles and larger ones.

The structure of an animal cell is characterized by the presence of cytoplasm, mostly consisting of water. The cytoplasm is a receptacle for organelles and inclusions. In addition, the cytoplasm also contains the cytoskeleton - protein filaments that are involved in the process delimit the intracellular space and maintain the cellular shape, the ability to contract. An important component of the cytoplasm is hyaloplasm, which determines the viscosity and elasticity of the cell structure. Depending on external and internal factors, hyaloplasm can change its viscosity - become liquid or gel-like.

Studying the structure of an animal cell, one cannot but pay attention to the cellular apparatus - the organelles that are in the cell. All organelles have their own specific structure, which is determined by the functions performed. The nucleus is the central cell unit that contains hereditary information and is involved in the metabolism in the cell itself. Cellular organelles include the endoplasmic reticulum, cell center, mitochondria, ribosomes, the Golgi complex, plastids, lysosomes, and vacuoles. There are similar organelles in any cell, but, depending on the function, the structure of an animal cell may differ in the presence of specific structures.

Organoids:

Mitochondria oxidize and store chemical energy;

Due to the presence of special enzymes, it synthesizes fats and carbohydrates, its channels contribute to the transport of substances inside the cell;

Ribosomes synthesize protein;

The Golgi complex concentrates the protein, compacts the synthesized fats, polysaccharides, forms lysosomes and prepares substances for their removal from the cell or direct use inside it;

Lysosomes break down carbohydrates, proteins, nucleic acids, and fats, essentially digesting the nutrients entering the cell;

The cell center is involved in the process of cell division;

Vacuoles, due to the content of cell sap, maintain cell turgor (internal pressure).

The structure of a living cell is extremely complex - at the cellular level, many biochemical processes take place, which together ensure the vital activity of the organism.

The cytoplasm is perhaps the most important part of any cell structure, representing a kind of "connective tissue" between all the components of the cell.

The functions and properties of the cytoplasm are diverse; its role in ensuring the life of the cell can hardly be overestimated.

This article describes most of the processes that occur in the smallest living structure at the macro level, where the main role is assigned to the gel-like mass that fills the internal volume of the cell and gives the latter its appearance and shape.

The cytoplasm is a viscous (jelly-like) transparent substance that fills every cell and is bounded by the cell membrane. It consists of water, salts, proteins and other organic molecules.

All eukaryotic organelles, such as the nucleus, endoplasmic reticulum, and mitochondria, are located in the cytoplasm. The part of it that is not contained in organelles is called the cytosol. Although it may seem that the cytoplasm has neither shape nor structure, in fact it is a highly organized substance, which is provided by the so-called cytoskeleton (protein structure). The cytoplasm was discovered in 1835 by Robert Brown and other scientists.

Chemical composition

Basically, the cytoplasm is the substance that fills the cell. This substance is viscous, gel-like, 80% water and is usually clear and colorless.

The cytoplasm is the substance of life, which is also called molecular soup, in which cellular organelles are in suspension and connected to each other by a two-layer lipid membrane. The cytoskeleton in the cytoplasm gives it its shape. The process of cytoplasmic flow ensures the movement of useful substances between organelles and the removal of waste products. This substance contains many salts and is a good conductor of electricity.

As stated, substance consists of 70-90% water and is colorless. Most cellular processes take place in it, for example, glycosis, metabolism, cell division processes. The outer transparent glassy layer is called ectoplasm or cell cortex, the inner part of the substance is called endoplasm. In plant cells, the process of cytoplasmic flow takes place, which is the flow of the cytoplasm around the vacuole.

Main characteristics

The following properties of the cytoplasm should be listed:

Structure and components

In prokaryotes (eg bacteria) that do not have a nucleus attached to a membrane, the cytoplasm represents the entire contents of the cell within the plasma membrane. In eukaryotes (for example, plant and animal cells), the cytoplasm is formed by three components that differ from each other: cytosol, organelles, various particles and granules, called cytoplasmic inclusions.

Cytosol, organelles, inclusions

Cytosol is a semi-liquid component located external to the nucleus and inside the plasma membrane. Cytosol makes up approximately 70% of the cell volume and consists of water, cytoskeletal fibers, salts, and organic and inorganic molecules dissolved in water. It also contains proteins and soluble structures such as ribosomes and proteasomes. The inner part of the cytosol, the most fluid and granular, is called the endoplasm.

The network of fibers and high concentrations of dissolved macromolecules, such as proteins, lead to the formation of macromolecular clusters, which greatly affect the transfer of substances between the components of the cytoplasm.

Organoid means "small organ" that is connected to a membrane. Organelles are located inside the cell and perform specific functions necessary to maintain the life of this smallest brick of life. Organelles are small cellular structures that perform specific functions. The following examples can be given:

mitochondria;
ribosomes;
core;
lysosomes;
chloroplasts (in plants);
endoplasmic reticulum;
golgi apparatus.

Inside the cell is also the cytoskeleton, a network of fibers that help it maintain its shape.

Cytoplasmic inclusions are particles that are temporarily suspended in a jelly-like substance and consist of macromolecules and granules. You can find three types of such inclusions: secretory, nutritional, pigment. Examples of secretory inclusions include proteins, enzymes and acids. Glycogen (glucose storage molecule) and lipids are prime examples of nutritional inclusions, melanin found in skin cells is an example of pigmented inclusions.

Cytoplasmic inclusions, being small particles suspended in the cytosol, represent a diverse range of inclusions present in various types of cells. These can be either calcium oxalate or silicon dioxide crystals in plants, or starch and glycogen granules. A wide range of inclusions are lipids having a spherical shape, present in both prokaryotes and eukaryotes, and serving for the accumulation of fats and fatty acids. For example, such inclusions occupy most of the volume of adiposites - specialized storage cells.

Functions of the cytoplasm in the cell

The most important functions can be represented in the form of the following table:

providing the shape of the cell;
habitat for organoids;
transport of substances;
supply of nutrients.

The cytoplasm serves to support organelles and cellular molecules. Many cellular processes take place in the cytoplasm. Some of these processes include protein synthesis, the first step in cellular respiration, which bears the name glycolysis, mitosis and meiosis processes. In addition, the cytoplasm helps hormones move around the cell, and waste products are also removed through it.

Most of the different actions and events take place in this gelatinous liquid, which contains enzymes that contribute to the decomposition of waste products, and many metabolic processes also take place here. The cytoplasm provides the cell with a form, filling it, helps to maintain the organelles in their places. Without it, the cell would look "deflated", and various substances could not easily move from one organelle to another.

Transport of substances

The liquid substance of the contents of the cell is very important for maintaining its vital activity, since allows easy exchange of nutrients between organelles. Such an exchange is due to the process of cytoplasmic flow, which is the flow of the cytosol (the most mobile and fluid part of the cytoplasm), carrying nutrients, genetic information and other substances from one organoid to another.

Some of the processes that take place in the cytosol include also metabolite transport. The organoid can produce amino acids, fatty acids, and other substances that travel through the cytosol to the organoid that needs these substances.

Cytoplasmic currents lead to the fact that the cell itself can move. Some of the smallest life structures are equipped with cilia (small, hair-like structures on the outside of the cell that allow the latter to move through space). For other cells, for example, amoeba, the only way to move is the movement of fluid in the cytosol.

Supply of nutrients

In addition to the transport of various material, the liquid space between organelles acts as a kind of storage chamber for these materials until the moment when they are really needed by one or another organoid. Within the cytosol, proteins, oxygen, and various building blocks are suspended. In addition to useful substances, the cytoplasm also contains metabolic products that are waiting for their turn until the removal process removes them from the cell.

plasma membrane

The cell, or plasma, membrane is a formation that prevents the cytoplasm from flowing out of the cell. This membrane is composed of phospholepids forming a lipid bilayer that is semi-permeable: only certain molecules can pass through this layer. Proteins, lipids, and other molecules can cross the cell membrane through the process of endocytosis, which forms a vesicle of these substances.

The bubble, which includes liquid and molecules, detaches from the membrane, forming an endosome. The latter moves inside the cell to its recipients. Waste products are excreted through the process of exocytosis. In this process, the vesicles formed in the Golgi apparatus are connected to the membrane, which pushes their contents into the environment. The membrane also provides the shape of the cell and serves as a support platform for the cytoskeleton and cell wall (in plants).

Plant and animal cells

The similarity of the internal contents of plant and animal cells speaks of their identical origin. The cytoplasm provides mechanical support to the internal structures of the cell, which are suspended in it.

The cytoplasm maintains the shape and consistency of the cell and contains many chemicals that are key to maintaining life processes and metabolism.

Metabolic reactions such as glycosis and protein synthesis take place in the jelly-like contents. In plant cells, unlike animals, there is a movement of the cytoplasm around the vacuole, which is known as cytoplasmic flow.

The cytoplasm of animal cells is a substance similar to a gel dissolved in water, it fills the entire volume of the cell and contains proteins and other important molecules necessary for life. The gel-like mass contains proteins, hydrocarbons, salts, sugars, amino acids and nucleotides, all cellular organelles and the cytoskeleton.

The gel-like content of the cell, limited by the membrane, is called the cytoplasm of a living cell. The concept was introduced in 1882 by the German botanist Eduard Strasburger.

Structure

The cytoplasm is the internal environment of any cell and is characteristic of cells of bacteria, plants, fungi, and animals.
The cytoplasm consists of the following components:

hyaloplasms (cytosols) - liquid substance;
cellular inclusions - optional components of the cell;
organoids - permanent components of the cell;
cytoskeleton - cell scaffold.

The chemical composition of the cytosol includes the following substances:

water - 85%;
proteins - 10%
organic compounds - 5%.

Organic compounds include:

mineral salts;
carbohydrates;
lipids;
nitrogen-containing compounds;
a small amount of DNA and RNA;
glycogen (characteristic of animal cells).

Rice. 1. The composition of the cytoplasm.

The cytoplasm contains a supply of nutrients (drops of fat, grains of polysaccharides), as well as insoluble waste products of the cell.

The cytoplasm is colorless and constantly moving, flowing. It contains all the organelles of the cell and carries out their relationship. With partial removal, the cytoplasm is restored. When the cytoplasm is completely removed, the cell dies.

The structure of the cytoplasm is heterogeneous. Conditionally allocate two layers of cytoplasm:

vitality

Cytoplasm is a vital substance involved in the main processes of the cell:

metabolism;
growth;
division.

The movement of the cytoplasm is called cyclosis or cytoplasmic flow. It is carried out in eukaryotic cells, including humans. During cyclosis, the cytoplasm delivers substances to all cell organelles, carrying out cellular metabolism. The cytoplasm moves through the cytoskeleton with the consumption of ATP.

With an increase in the volume of the cytoplasm, the cell grows. The process of dividing the body of a eukaryotic cell after nuclear division (karyokinesis) is called cytokinesis. As a result of division of the body, the cytoplasm, together with organelles, is distributed between two daughter cells.

Rice. 2. Cytokinesis.

Functions

The main functions of the cytoplasm in the cell are described in the table.

The separation of the cytoplasm from the membrane by osmosis of water escaping to the outside is called plasmolysis. The reverse process - deplasmolysis - occurs when a sufficient amount of water enters the cell. Processes are characteristic of any cell, except for the animal.

Average rating: 4.7. Total ratings received: 77.

Unlike eukaryotic and fungi, animal cells do not have. This feature was lost in the distant past by single-celled organisms that gave rise to. Most cells, both animal and plant, are between 1 and 100 µm (micrometers) in size and are therefore only visible with a microscope.

The earliest fossil evidence of animals dates from the Vendian period (650-454 million years ago). The first ended with this period, but during the ensuing period, an explosion of new life forms resulted in many of the major faunal groups known today. There is evidence that animals appeared before the early (505-438 million years ago).

The structure of animal cells

Diagram of the structure of an animal cell

- self-reproducing organelles consisting of nine bundles of microtubules and found only in animal cells. They help in the organization of cell division, but are not essential for this process.
are required for cell movement. In multicellular organisms, cilia function to move fluid or substances around an immobile cell, or to a group of cells.
- a network of sacs that produces, processes and transports chemical compounds inside and outside the cell. It is associated with a two-layer nuclear envelope that provides a conduit between the core and.
Endosomes are membrane-bound vesicles formed by a set of complex processes known as , and are found in the cytoplasm of almost any animal cell. The main mechanism of endocytosis is the reverse of what occurs during or during cellular secretion.
- Department of distribution and delivery of cell chemicals. It modifies proteins and fats embedded in the endoplasmic reticulum and prepares them for export outside the cell.
Intermediate filaments are a broad class of fibrous proteins that play an important role as both structural and functional elements.

Divides all cells (or alive organisms) into two types: prokaryotes And eukaryotes. Prokaryotes are non-nuclear cells or organisms, which include viruses, prokaryotic bacteria and blue-green algae, in which the cell consists directly of the cytoplasm, in which one chromosome is located - DNA molecule(sometimes RNA).

eukaryotic cells have a nucleus in which there are nucleoproteins (histone protein + DNA complex), as well as others organelles. Eukaryotes include most of the modern unicellular and multicellular living organisms known to science (including plants).

The structure of eukaryotic organoids.

Organoid name	The structure of the organoid	Organoid functions
Cytoplasm	The internal environment of the cell, which contains the nucleus and other organelles. It has a semi-liquid, fine-grained structure.	Performs a transport function. Regulates the rate of flow of metabolic biochemical processes. Provides interaction between organelles.
Ribosomes	Small spherical or ellipsoidal organelles with a diameter of 15 to 30 nanometers.	They provide the process of synthesis of protein molecules, their assembly from amino acids.
Mitochondria	Organelles that have a wide variety of shapes - from spherical to filamentous. Inside the mitochondria there are folds from 0.2 to 0.7 microns. The outer shell of mitochondria has a two-membrane structure. The outer membrane is smooth, and on the inner there are outgrowths of a cruciform shape with respiratory enzymes.	Enzymes on membranes ensure the synthesis of ATP (adenosine triphosphoric acid). Energy function. Mitochondria supply energy to the cell by releasing it during the breakdown of ATP.
Endoplasmic reticulum (ER)	The membrane system in the cytoplasm that forms channels and cavities. There are two types: granular, on which there are ribosomes and smooth.	Provides processes for the synthesis of nutrients (proteins, fats, carbohydrates). Proteins are synthesized on granular ER, while fats and carbohydrates are synthesized on smooth ER. Provides circulation and delivery of nutrients within the cell.
plastids(organelles peculiar only to plant cells) are of three types:	Double membrane organelles
Leucoplasts	Colorless plastids found in tubers, roots and bulbs of plants.	They are an additional reservoir for storing nutrients.
Chloroplasts	Organelles are oval in shape and green in color. They are separated from the cytoplasm by two three-layer membranes. Inside the chloroplasts is chlorophyll.	Transform organic matter from inorganic matter using the energy of the sun.
Chromoplasts	Organelles, from yellow to brown, in which carotene accumulates.	They contribute to the appearance of parts with yellow, orange and red color in plants.
Lysosomes	Rounded organelles with a diameter of about 1 micron, having a membrane on the surface, and inside - a complex of enzymes.	digestive function. Digest nutrient particles and eliminate dead parts of the cell.
Golgi complex	It may be of different shapes. Consists of cavities separated by membranes. Tubular formations with bubbles at the ends depart from the cavities.	Forms lysosomes. Collects and removes organic substances synthesized in EPS.
Cell Center	It consists of a centrosphere (a compacted area of the cytoplasm) and centrioles - two small bodies.	Performs an important function for cell division.
Cell inclusions	Carbohydrates, fats and proteins, which are non-permanent components of the cell.	Spare nutrients that are used for the life of the cell.
Organelles of movement	Flagella and cilia (outgrowths and cells), myofibrils (filamentous formations) and pseudopodia (or pseudopodia).	They perform a motor function, and also provide the process of muscle contraction.

cell nucleus is the main and most complex organelle of the cell, so we will consider it