The structure of an animal cell with symbols. Structural units of all tissues and organs of the cell

The cell is the smallest structure of the entire plant and animal world - 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 collection of certain cells forms tissues, tissues form organs, and those form organ systems. The structure of the animal is similar in many ways, but at the same time it has fundamental differences. For example, the chemical composition of cells is similar, the principles of structure and vital activity are similar, but in plant cells there are no centrioles (except for algae), and starch serves as a nutritional reserve base.

An animal is based on three main components - nucleus, cytoplasm and cell membrane. Together with the nucleus, the cytoplasm forms protoplasm. The cell membrane is a biological membrane (septum) 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, you can easily see the structure of an animal cell. The cell membrane 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 there is a special structure - the glycocalyx, which provides the selective ability of the membrane. The shell allows necessary substances to pass through and retains those that cause harm. The structure of an animal cell is aimed at ensuring a protective function already at this level. 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 allows both small and larger particles to pass through.

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

When studying the structure of an animal cell, one cannot help but pay attention to the cellular apparatus - the organelles that are located in the cell. All organelles have their own specific structure, which is determined by the functions they perform. The nucleus is the central cellular unit, which contains hereditary information and is involved in metabolism in the cell itself. Cellular organelles include the endoplasmic reticulum, cell center, mitochondria, ribosomes, Golgi complex, plastids, lysosomes, vacuoles. Similar organelles are found 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 accumulate chemical energy;

Thanks to the presence of special enzymes, it synthesizes fats and carbohydrates; its channels facilitate the transport of substances within the cell;

Ribosomes synthesize protein;

The Golgi complex concentrates protein, compacts 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 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 - many biochemical processes take place at the cellular level, which together ensure the vital functions of the organism.

Cytoplasm is perhaps the most important part of any cellular 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 occurring in the smallest living structure at the macro level, where the main role is played by the gel-like mass that fills the internal volume of the cell and gives it its appearance and shape.

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

All organelles of eukaryotes, 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 cytosol. Although it may seem that the cytoplasm has neither shape nor structure, it is actually 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

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

Cytoplasm is the substance of life, also called molecular soup, in which cellular organelles are suspended and connected to each other by a bilayer lipid membrane. The cytoskeleton, located 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 was said, substance consists of 70−90% water and is colorless. Most cellular processes occur 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 cytoplasm around the vacuole.

Main characteristics

The following properties of the cytoplasm should be listed:

Structure and components

In prokaryotes (such as bacteria), which do not have a membrane-bound nucleus, 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 distinct components: the cytosol, organelles, and various particles and granules called cytoplasmic inclusions.

Cytosol, organelles, inclusions

The cytosol is a semi-liquid component located external to the nucleus and internal to the plasma membrane. The cytosol makes up approximately 70% of the cell volume and consists of water, cytoskeletal fibers, salts, and organic and inorganic molecules dissolved in water. 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 aggregates, which strongly influence the transfer of substances between the components of the cytoplasm.

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

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

Inside the cell there is also a 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. Three types of such inclusions can be found: secretory, nutritious, and pigmented. Examples of secretory inclusions include proteins, enzymes and acids. Glycogen (the storage molecule for glucose) and lipids are prime examples of nutrient inclusions, and melanin found in skin cells is an example of pigment inclusions.

Cytoplasmic inclusions, being small particles suspended in the cytosol, represent a diverse range of inclusions present in different types of cells. These can be either crystals of calcium oxalate or silicon dioxide in plants, or granules of starch and glycogen. A wide range of inclusions are lipids that have a spherical shape, are present in both prokaryotes and eukaryotes, and serve 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 presented in the following table:

• ensuring the shape of the cell;
• habitat of organelles;
• transport of substances;
• supply of nutrients.

Cytoplasm serves to support organelles and cellular molecules. Many cellular processes occur in the cytoplasm. Some of these processes include protein synthesis, the first stage of cellular respiration, which is called glycolysis, processes of mitosis and meiosis. In addition, the cytoplasm helps hormones move throughout the cell, and waste products are also removed through it.

Most of the different actions and events take place in this gelatin-like liquid, which contains enzymes that promote the decomposition of waste products, and many metabolic processes also take place here. Cytoplasm provides the cell with shape, filling it, and helps maintain the organelles in their places. Without it, the cell would appear "deflated" and various substances could not easily move from one organelle to another.

Transport of substances

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

Some of the processes that occur in the cytosol also include metabolite transfer. The organelle can produce amino acid, fatty acid and other substances, which move through the cytosol to the organelle that needs these substances.

Cytoplasmic flows lead to 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 cell to move through space). For other cells, for example, amoeba, the only way to move is the movement of fluid in the cytosol.

Nutrient supply

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

Plasma membrane

The cell, or plasma, membrane is a formation that prevents the flow of cytoplasm from the cell. This membrane is composed of phospholipids that form a lipid bilayer, which is semi-permeable: only certain molecules can penetrate this layer. Proteins, lipids, and other molecules can cross the cell membrane through the process of endocytosis, which produces a vesicle containing these substances.

A vesicle containing fluid and molecules breaks away from the membrane, forming an endosome. The latter moves inside the cell to its recipients. Waste products are eliminated through the process of exocytosis. In this process, vesicles formed in the Golgi apparatus connect to a membrane, which pushes their contents into the environment. The membrane also provides the cell with shape and serves as a supporting platform for the cytoskeleton and cell wall (in plants).

Plant and animal cells

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

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

Metabolic reactions such as glycosis and protein synthesis occur in the jelly-like contents. In plant cells, unlike animal cells, there is a movement of 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 contents of the cell, bounded by a membrane, are called the cytoplasm of a living cell. The concept was introduced in 1882 by the German botanist Eduard Strassburger.

Structure

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

• hyaloplasm (cytosols) - liquid substance;
• cellular inclusions - optional components of the cell;
• organelles - permanent components of the cell;
• cytoskeleton - cell framework.

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. 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 moves and flows. It contains all the organelles of the cell and mediates their interconnection. When partially removed, 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:

TOP 4 articleswho are reading along with this

• ectoplasm (plasmagel) - an outer dense layer that does not contain organelles;
• endoplasm (plasmasol) - an internal, more liquid layer containing organelles.

The division into ectoplasm and endoplasm is clearly expressed in protozoa. Ectoplasm helps the cell move.

Outside, the cytoplasm is surrounded by a cytoplasmic membrane or plasmalemma. It protects the cell from damage, carries out selective transport of substances and provides cell irritability. The membrane consists of lipids and proteins.

Life activity

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 occurs in eukaryotic cells, including humans. During cyclosis, the cytoplasm delivers substances to all organelles of the cell, carrying out cellular metabolism. The cytoplasm moves through the cytoskeleton with the consumption of ATP.

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

Rice. 2. Cytokinesis.

Functions

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

The separation of the cytoplasm from the membrane by osmosis of water coming out is called plasmolysis. The reverse process - deplasmolysis - occurs when a sufficient amount of water enters the cell. The processes are characteristic of any cell except animal cells.

Average rating: 4.7. Total ratings received: 77.

Unlike eukaryotic and fungal cells, 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, range in size from 1 to 100 µm (micrometers) 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 subsequent period, an explosion of new life forms gave rise to 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

Animal cell structure diagram

• - self-replicating organelles consisting of nine bundles of microtubules and found only in animal cells. They help organize cell division, but are not essential for this process.
• - necessary for cell movement. In multicellular organisms, cilia function to move fluid or substances around a stationary cell, or for or groups 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, providing a pipeline between the core and.
• Endosomes are membrane-bound vesicles formed by a complex set of processes known as endosomes, and are found in the cytoplasm of almost any animal cell. The basic mechanism of endocytosis is the opposite of what occurs during or cellular secretion.
• - department of distribution and delivery of cell chemicals. It modifies proteins and fats embedded in the endoplasmic reticulum and also prepares them for export outside the cell.
• Intermediate filaments are a broad class of fibrous proteins that play important roles as both structural and functional elements.

Divides all cells (or alive organisms) into two types: prokaryotes And eukaryotes. Prokaryotes are nuclear-free 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 core containing nucleoproteins (histone protein + DNA complex), as well as others organoids. Eukaryotes include the majority of modern unicellular and multicellular living organisms known to science (including plants).

The structure of eukaryotic granoids.

Organoid name	Organoid structure	Functions of the organoid
Cytoplasm	The internal environment of a cell in which the nucleus and other organelles are located. It has a semi-liquid, fine-grained structure.	Performs a transport function. Regulates the speed of metabolic biochemical processes. Provides interaction between organelles.
Ribosomes	Small organoids of spherical or ellipsoidal shape with a diameter of 15 to 30 nanometers.	They provide the process of synthesis of protein molecules and 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 µm. The outer shell of mitochondria has a double-membrane structure. The outer membrane is smooth, and on the inner there are cross-shaped outgrowths with respiratory enzymes.	Enzymes on membranes provide the synthesis of ATP (adenosine triphosphoric acid). Energy function. Mitochondria provide energy to the cell by releasing it during the breakdown of ATP.
Endoplasmic reticulum (ER)	A system of membranes in the cytoplasm that forms channels and cavities. There are two types: granular, which has ribosomes, and smooth.	Provides processes for the synthesis of nutrients (proteins, fats, carbohydrates). Proteins are synthesized on granular EPS, while fats and carbohydrates are synthesized on smooth EPS. Provides circulation and delivery of nutrients within the cell.
Plastids(organelles characteristic only of plant cells) are of three types:	Double membrane organelles
Leukoplasts	Colorless plastids that are found in tubers, roots and bulbs of plants.	They are an additional reservoir for storing nutrients.
Chloroplasts	Organelles are oval-shaped and green in color. They are separated from the cytoplasm by two three-layer membranes. Chloroplasts contain chlorophyll.	They convert organic substances from inorganic ones using solar energy.
Chromoplasts	Organelles, yellow to brown in color, in which carotene accumulates.	Promote the appearance of yellow, orange and red colored parts in plants.
Lysosomes	Organelles are round in shape with a diameter of about 1 micron, having a membrane on the surface and a complex of enzymes inside.	Digestive function. They digest nutrient particles and eliminate dead parts of the cell.
Golgi complex	May be of different shapes. Consists of cavities delimited by membranes. Tubular formations with bubbles at the ends extend from the cavities.	Forms lysosomes. Collects and removes organic substances synthesized in EPS.
Cell center	It consists of a centrosphere (a dense section of the cytoplasm) and centrioles - two small bodies.	Performs an important function for cell division.
Cellular inclusions	Carbohydrates, fats and proteins, which are non-permanent components of the cell.	Spare nutrients that are used for cell functioning.
Organoids of movement	Flagella and cilia (outgrowths and cells), myofibrils (thread-like formations) and pseudopodia (or pseudopods).	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