Brief description of the cytoplasm. Cytoplasm. Functions of the cytoplasm. The structure of the cytoplasm. Difference between the cytoplasm of animal and plant cells

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.

In contact with

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

Should be listed following properties cytoplasm:

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. Interior the cytosol, the most fluid and granular, is called 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 (glucose storage molecule) and lipids - vivid examples nutritional inclusions, 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 makes it easy to share 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 chemical substances, which 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.

Lesson objectives:

• Deepen the general understanding of the structure of a eukaryotic cell.
• Formulate knowledge about the properties and functions of the cytoplasm.
• In practical work, make sure that the cytoplasm of a living cell is elastic and semi-permeable.

During the classes

• Write down the topic of the lesson.
• We review the material we have covered and work on tests.
• We read and comment on the test questions. (Cm. Annex 1).
• Let's write it down homework: clause 5.2., notes in notebooks.
• Learning new material.

This is the main substance of the cytoplasm.

This is a complex colloidal system.

Consists of water, proteins, carbohydrates, nucleic acids, lipids, inorganic substances.

There is a cytoskeleton.

The cytoplasm is constantly moving.

Functions of the cytoplasm.

• Internal environment of the cell.
• Unites all cellular structures.
• Determines the location of organelles.
• Provides intracellular transport.

Properties of the cytoplasm:

• Elasticity.
• Semi-permeable.

Thanks to these properties, the cell tolerates temporary dehydration and maintains the constancy of its composition.

It is necessary to remember such concepts as turgor, osmosis, diffusion.

In order to become familiar with the properties of the cytoplasm, students are asked to complete practical work: "Study of plasmolysis and deplasmolysis in a plant cell. (See Appendix 2).

In the process of work, you need to draw a cell of the onion skin (Point 1. The cell in points 2 and 3).

Draw a conclusion about the processes occurring in the cell (orally)

The guys are trying to explain what is observed in point 2 plasmolysis separation of the parietal layer of the cytoplasm, at point 3 there is deplasmolysis- return of the cytoplasm to its normal state.

It is necessary to explain the reasons for these phenomena. To relieve difficulties before lessons, I give three students teaching aids: "Biological Encyclopedic Dictionary", 2nd volume of biology by N. Green, "Experiment in Plant Physiology" by E.M. Vasiliev, where they independently find material about the causes plasmolysis And deplasmolysis.

It turns out that the cytoplasm is elastic and semi-permeable. If it were permeable, then the concentrations of cell sap and hypertonic solution would be equalized through the diffuse movement of water and solutes from the cell to the solution and back. However, the cytoplasm, having the property of semi-permeability, does not allow substances dissolved in water to pass into the cell.

On the contrary, only water, according to the laws of osmosis, will be sucked out of the cell by a hypertonic solution, i.e. move through semi-permeable cytoplasm. The volume of the vacuole will decrease. Due to its elasticity, the cytoplasm follows the contracting vacuole and lags behind the cell membrane. This is what happens plasmolysis.

When a plasmolyzed cell is immersed in water, deplasmolysis is observed.

Summarizing the knowledge gained in the lesson.

1. What functions are inherent in the cytoplasm?
2. Properties of the cytoplasm.
3. The meaning of plasmolysis and deplasmolysis.
4. Cytoplasm is
   A) water solution salts and organic substances together with cell organelles, but without a nucleus;
   b) a solution of organic substances, including the cell nucleus;
   c) an aqueous solution of minerals, including all cell organelles with a nucleus.
5. What is the main substance of the cytoplasm called?

During practical work The teacher checks the correctness of its implementation. Whoever succeeded can give marks. Marks are given for correct conclusions.

The chemical composition of the cytoplasm is based on water - 60-90%, organic and inorganic compounds. The cytoplasm is in an alkaline reaction. The peculiarity of this substance is constant movement or cyclosis, which becomes a necessary condition cell life. Metabolic processes occur in the hyaloplasm, a colorless, thick colloid. Thanks to the hyaloplasm, the relationship between the nucleus and organelles is carried out.

The hyaloplasm includes the endoplasmic reticulum or reticulum, this is a branched system of tubes, channels and cavities that are delimited by a single membrane. Mitochondria, the special energy stations of the cell, have the shape of legumes. Ribosomes are organelles that contain RNA. Another cytoplasmic organelle is the Golgi complex, named after the Italian Golgi. Small organelles in the shape of spheres are lysosomes. Plant cells contain. The cavities with cell sap are called vacuoles. There are many of them in the cells of plant fruits. Outgrowths of the cytoplasm are many organelles of movement - strands, cilia, pseudopods.

Functions of the components of the cytoplasm

The reticulum provides the creation of a “framework” for mechanical strength and gives the cell shape, that is, it has a shape-forming function. On its walls there are enzymes and enzyme-substrate complexes, on which the implementation of a biochemical reaction depends. Transfer occurs through the reticulum channels chemical compounds, thus it performs a transport function.

Mitochondria help break down complex organic substances. This releases the energy that the cell needs to maintain physiological processes.

Ribosomes are responsible for the synthesis of protein molecules.

The Golgi complex or apparatus performs a secretory function in animal cells and regulates metabolism. In plants, the complex plays the role of a center for the synthesis of polysaccharides, which are located in the cell walls.

Plastids can be of three types. Chloroplasts or green plastids are involved in photosynthesis. A plant cell can contain up to 50 chloroplasts. Chromoplasts contain pigments - anthocyanin and carotenoid. These plastids are responsible for the color of plants in order to attract animals and protect them. Leukoplasts provide the accumulation of nutrients, they can also form chromoplasts and chloroplasts.

Vacuoles are places where nutrients accumulate. They also provide the shape-forming function of the cell, creating internal pressure.

Various solid and liquid inclusions represent reserve substances and substances for excretion.

Movement organelles ensure the movement of cells in space. They are outgrowths of the cytoplasm, found in single-celled organisms, germ cells, phagocytes.

Cytoplasm

Cytoplasm- an obligatory part of the cell, enclosed between the plasma membrane and the nucleus; is divided into hyaloplasm (the main substance of the cytoplasm), organelles (permanent components of the cytoplasm) and inclusions (temporary components of the cytoplasm). Chemical composition of the cytoplasm: the basis is water (60–90% of the total mass of the cytoplasm), various organic and inorganic compounds. The cytoplasm has an alkaline reaction. Feature The cytoplasm of a eukaryotic cell is in constant motion (cyclosis). It is detected primarily by the movement of cell organelles, such as chloroplasts. If the movement of the cytoplasm stops, the cell dies, since only by being in constant motion can it perform its functions.

Hyaloplasma(cytosol) is a colorless, slimy, thick and transparent colloidal solution. It is in it that all metabolic processes take place, it ensures the interconnection of the nucleus and all organelles. Depending on the predominance of the liquid part or large molecules in the hyaloplasm, two forms of hyaloplasm are distinguished: sol - more liquid hyaloplasm and gel - thicker hyaloplasm. Mutual transitions are possible between them: the gel turns into a sol and vice versa.

Functions of the cytoplasm:

combining all cell components into a single system,

environment for the passage of many biochemical and physiological processes,

environment for the existence and functioning of organelles.

Cell membranes limit eukaryotic cells.

In each cell membrane, at least two layers can be distinguished. The inner layer is adjacent to the cytoplasm and is represented by plasma membrane(synonyms - plasmalemma, cell membrane, cytoplasmic membrane), over which is formed outer layer. IN animal cell it's thin and it's called glycocalyx(formed by glycoproteins, glycolipids, lipoproteins), in a plant cell - thick, called cell wall(formed by cellulose).

Membrane structure

All biological membranes have common structural features and properties. Currently, the liquid-mosaic model of membrane structure is generally accepted. The basis of the membrane is a lipid bilayer formed mainly by phospholipids. Phospholipids are triglycerides in which one fatty acid residue is replaced by a phosphoric acid residue; the section of the molecule containing the phosphoric acid residue is called the hydrophilic head, the sections containing the fatty acid residues are called the hydrophobic tails. In the membrane, phospholipids are arranged in a strictly ordered manner: the hydrophobic tails of the molecules face each other, and the hydrophilic heads face outward, towards the water.

In addition to lipids, the membrane contains proteins (on average ≈ 60%). They determine most of the specific functions of the membrane (transport of certain molecules, catalysis of reactions, receiving and converting signals from environment and etc.). There are: 1) peripheral proteins (located on the outer or inner surface lipid bilayer), 2) semi-integral proteins (immersed in the lipid bilayer on different depths), 3) integral, or transmembrane, proteins (penetrate the membrane through, contacting both the external and internal environment of the cell). Integral proteins are in some cases called channel-forming or channel proteins, since they can be considered as hydrophilic channels through which polar molecules pass into the cell (the lipid component of the membrane would not let them through).

Membrane structure: A - hydrophilic phospholipid head; B - hydrophobic phospholipid tails; 1 - hydrophobic regions of proteins E and F; 2 - hydrophilic regions of protein F; 3 - branched oligosaccharide chain attached to a lipid in a glycolipid molecule (glycolipids are less common than glycoproteins); 4 - branched oligosaccharide chain attached to a protein in a glycoprotein molecule; 5 - hydrophilic channel (functions as a pore through which ions and some polar molecules can pass).

The membrane may contain carbohydrates (up to 10%). The carbohydrate component of membranes is represented by oligosaccharide or polysaccharide chains associated with protein molecules (glycoproteins) or lipids (glycolipids). Carbohydrates are mainly located on the outer surface of the membrane. Carbohydrates provide receptor functions of the membrane. In animal cells, glycoproteins form a supra-membrane complex, the glycocalyx, which is several tens of nanometers thick. It contains many cell receptors, and with its help cell adhesion occurs.

Molecules of proteins, carbohydrates and lipids are mobile, capable of moving in the plane of the membrane. The thickness of the plasma membrane is approximately 7.5 nm.

Membrane functions:

separation of cellular contents from the external environment,

regulation of metabolism between the cell and the environment,

division of the cell into compartments (“compartments”),

· place of localization of “enzymatic conveyors”,

· ensuring communication between cells in the tissues of multicellular organisms (adhesion),

· signal recognition.

The most important property of membranes is selective permeability, i.e. membranes are highly permeable to some substances or molecules and poorly permeable (or completely impermeable) to others. This property underlies the regulatory function of membranes, ensuring the exchange of substances between the cell and the external environment.

The process of substances passing through the cell membrane is called substance transport. There are: 1) passive transport - the process of passage of substances that occurs without energy consumption; 2) active transport - the process of passage of substances that occurs with the expenditure of energy.

With passive transport substances move from an area of ​​higher concentration to an area of ​​lower, i.e. along the concentration gradient. In any solution there are solvent and solute molecules. The process of moving solute molecules is called diffusion, the movement of solvent molecules is called osmosis. If the molecule is charged, then its transport is also affected by the electrical gradient. Therefore, people often talk about an electrochemical gradient, combining both gradients together. The speed of transport depends on the magnitude of the gradient.

The following can be distinguished types of passive transport:

1) simple diffusion - transport of substances directly through the lipid bilayer (oxygen, carbon dioxide);

2) diffusion through membrane channels - transport through channel-forming proteins (Na+, K+, Ca2+, Cl-);

3) facilitated diffusion - transport of substances using special transport proteins, each of which is responsible for the movement of certain molecules or groups of related molecules (glucose, amino acids, nucleotides);

4) osmosis - transport of water molecules (in all biological systems the solvent is water).

Necessity active transport occurs when it is necessary to ensure the transport of molecules across a membrane against an electrochemical gradient. This transport is carried out by special carrier proteins, the activity of which requires energy expenditure. The energy source is ATP molecules.

Active transport includes:

1) Na+/K+ pump (sodium-potassium pump),

2) endocytosis,

3) exocytosis.

Na+/K+ pump operation. For normal functioning, the cell must maintain a certain ratio of K+ and Na+ ions in the cytoplasm and in external environment. The concentration of K+ inside the cell should be significantly higher than outside it, and Na+ - vice versa. It should be noted that Na+ and K+ can diffuse freely through membrane pores. The Na+/K+ pump counteracts the equalization of the concentrations of these ions and actively pumps Na+ out of the cell and K+ into the cell. The Na+/K+ pump is a transmembrane protein capable of conformational changes, as a result of which it can accept both K+ and Na+.

The Na+/K+ pump operating cycle can be divided into the following phases:

1) addition of Na+ with inside membranes,

2) phosphorylation of the pump protein,

3) release of Na+ in the extracellular space,

4) attachment of K+ from the outside of the membrane,

5) dephosphorylation of the pump protein,

6) release of K+ in the intracellular space. Almost a third of all energy required for cell functioning is spent on the operation of the sodium-potassium pump. In one cycle of operation, the pump pumps out 3Na+ from the cell and pumps in 2K+.

Endocytosis- the process of absorption of large particles and macromolecules by the cell.

There are two types of endocytosis:

1) phagocytosis - capture and absorption of large particles (cells, parts of cells, macromolecules),

2) pinocytosis - capture and absorption of liquid material (solution, colloidal solution, suspension).

Phenomenon phagocytosis openly I.I. Mechnikov in 1882. endocytosis the plasma membrane forms an invagination, its edges merge, and structures separated from the cytoplasm by a single membrane are laced into the cytoplasm. Many protozoa and some leukocytes are capable of phagocytosis. Pinocytosis observed in intestinal epithelial cells, in the endothelium of blood capillaries.

Exocytosis- a process reverse to endocytosis: the removal of various substances from the cell. During exocytosis, the vesicle membrane merges with the outer cytoplasmic membrane, the contents of the vesicle are removed outside the cell, and its membrane is included in the outer cytoplasmic membrane. In this way, hormones are removed from the cells of the endocrine glands; in protozoa, undigested food remains are removed.

Lecture No. 7.

Related information.

It is known that most living beings consist of 70 percent or more water in free or bound form. Where does so much of it come from, where is it localized? It turns out that each cell contains up to 80% water, and only the rest is dry matter.

And the main “water” structure is the cytoplasm of the cell. This is a complex, heterogeneous, dynamic internal environment, the structural features and functions of which we will get acquainted with further.

Protoplast

This term is usually used to designate the entire internal contents of any eukaryotic smallest structure, separated by the plasma membrane from its other “colleagues”. That is, this includes the cytoplasm - the internal environment of the cell, the organelles located in it, the nucleus with nucleoli and genetic material.

What organelles are located inside the cytoplasm? This:

• ribosomes;
• mitochondria;
• Golgi apparatus;
• lysosomes;
• vacuoles (in plants and fungi);
• cell center;
• plastids (in plants);
• cilia and flagella;
• microfilaments;
• microtubules.

The nucleus, separated by the karyolemma, has nucleoli and also contains the cytoplasm of the cell. It is in the center in animals, closer to the wall in plants.

Thus, the structural features of the cytoplasm will largely depend on the type of cell, on the organism itself, and its membership in the kingdom of living beings. In general, it occupies all the free space inside and performs a number of important functions.

Matrix or hyaloplasm

The structure of the cell cytoplasm consists primarily of its division into parts:

• hyaloplasm - permanent liquid part;
• organoids;
• inclusions are structure variables.

The matrix, or hyaloplasm, is the main internal component, which can be in two states - ash and gel.

Cytosol is the cytoplasm of a cell that has a more liquid aggregate character. Cytogel is the same thing, but in a thicker state, rich in large molecules of organic substances. General chemical composition and physical properties hyaloplasmas are expressed as follows:

• colorless, viscous colloidal substance, quite thick and slimy;
• has a clear differentiation according to structural organization, however, due to mobility, it can easily change it;
• from the inside it is represented by a cytoskeleton or microtrabecular lattice, which is formed by protein filaments (microtubules and microfilaments);
• All structural parts of the cell as a whole are located on parts of this lattice, and due to microtubules, the Golgi apparatus and the ER, communication occurs between them through the hyaloplasm.

Thus, hyaloplasm is an important part that provides many of the functions of the cytoplasm in the cell.

Composition of the cytoplasm

If speak about chemical composition, then the share of water in the cytoplasm accounts for about 70%. This is an average value, because some plants have cells that contain up to 90-95% water. Dry matter is presented:

General chemical reaction environments - alkaline or slightly alkaline. If we consider how the cytoplasm of a cell is located, then this feature should be noted. Part is collected at the edge, in the area of ​​the plasmalemma, and is called ectoplasm. The other part is oriented closer to the karyolemma and is called endoplasm.

The structure of the cell cytoplasm is determined special structures- microtubules and microfilaments, so let’s look at them in more detail.

Microtubules

Hollow small elongated particles up to several micrometers in size. Diameter - from 6 to 25 nm. Due to too meager indicators, a complete and comprehensive study of these structures is not yet possible, but it is assumed that their walls consist of the protein substance tubulin. This compound has a chain-linked helical molecule.

Some functions of the cytoplasm in the cell are performed precisely due to the presence of microtubules. For example, they participate in the formation of fungi and plants, and some bacteria. There are much fewer of them in animal cells. Also, it is these structures that carry out the movement of organelles in the cytoplasm.

Microtubules themselves are unstable and can quickly disintegrate and form again, being renewed from time to time.

Microfilaments

Enough important elements cytoplasm. They are long filaments of actin (globular protein), which, intertwined with each other, form a common network - the cytoskeleton. Another name is microtrabecular lattice. These are some kind of structural features of the cytoplasm. After all, it is thanks to this cytoskeleton that all organelles are held together, they can safely communicate with each other, substances and molecules pass through them, and metabolism takes place.

However, it is known that the cytoplasm is the internal environment of a cell, which is often capable of changing its physical properties: becoming more liquid or viscous, changing structure (transition from sol to gel and back). In this regard, microfilaments are a dynamic, labile part that can quickly rearrange, modify, disintegrate and form again.

Plasma membranes

The presence of well-developed and normally functioning numerous membrane structures is important for the cell, which also constitutes a kind of structural feature of the cytoplasm. After all, it is through plasma membrane barriers that the transport of molecules, nutrients and metabolic products, gases for respiration processes, and so on occurs. This is why most organelles have these structures.

They, like a network, are located in the cytoplasm and delimit the internal contents of their hosts from each other and from the environment. Protect and protect against unwanted substances and bacteria that pose a threat.

The structure of most of them is similar - a liquid-mosaic model, which considers each plasmalemma as a biolayer of lipids, permeated with different protein molecules.

Since the functions of the cytoplasm in a cell are primarily a transport connection between all its parts, the presence of membranes in most organelles is one of the structural parts of the hyaloplasm. Collectively, all together, they perform common tasks to ensure the life of the cell.

Ribosomes

Small (up to 20 nm) rounded structures consisting of two halves - subunits. These halves can exist either together or separate for some time. The basis of the composition: and protein. The main places of localization of ribosomes in the cell:

The functions of these structures are the synthesis and assembly of protein macromolecules, which are spent on the life of the cell.

and Golgi apparatus

A numerous network of tubules, tubes and vesicles, forming a conducting system inside the cell and located throughout the entire volume of the cytoplasm, is called the endoplasmic reticulum, or reticulum. Its function corresponds to its structure - ensuring the interconnection of organelles with each other and transporting nutritional molecules to the organelles.

The Golgi complex, or apparatus, performs the function of accumulating necessary substances (carbohydrates, fats, proteins) in a system of special cavities. They are limited from the cytoplasm by membranes. Also, this organelle is the site of synthesis of fats and carbohydrates.

Peroxisomes and lysosomes

Lysosomes are small, round structures resembling vesicles filled with liquid. They are very numerous and distributed in the cytoplasm, where they move freely within the cell. the main task theirs is the dissolution of foreign particles, that is, the elimination of “enemies” in the form of dead sections of cellular structures, bacteria and other molecules.

The liquid contents are saturated with enzymes, so lysosomes take part in the breakdown of macromolecules into their monomer units.

Peroxisomes are small oval or round organelles with a single membrane. Filled with liquid contents, including a large number of various enzymes. They are one of the main consumers of oxygen. They perform their functions depending on the type of cell in which they are located. Possible synthesis of myelin for the sheath nerve fibers, and can also carry out oxidation and neutralization of toxic substances and various molecules.

Mitochondria

It is not for nothing that these structures are called the power (energy) stations of the cell. After all, it is in them that the formation of the main energy carriers occurs - molecules of adenosine triphosphoric acid, or ATP. By appearance resemble beans. The membrane limiting the mitochondrion from the cytoplasm is double. The internal structure is highly folded to increase the surface area for ATP synthesis. The folds are called cristae and contain a large number of different enzymes for catalyzing synthesis processes.

Muscle cells in animal and human organisms have the most mitochondria, since they require increased energy content and consumption.

Cyclosis phenomenon

The movement of cytoplasm in a cell is called cyclosis. It consists of several types:

• oscillatory;
• rotational or circular;
• flowy.

Any movement is necessary to ensure a number of important functions of the cytoplasm: complete movement of organelles within the hyaloplasm, uniform exchange of nutrients, gases, energy, and excretion of metabolites.

Cyclosis occurs in both plant and animal cells, without exception. If it stops, the body dies. That's why this process- it is also an indicator of the vital activity of creatures.

Thus, we can conclude that the cytoplasm of any eukaryotic animal is a very dynamic, living structure.

Difference between the cytoplasm of animal and plant cells

In fact, there are few differences. The general plan of the structure and the functions performed are completely similar. However, there are still some discrepancies. For example:

In other respects, both structures are identical in composition and structure of the cytoplasm. The number of certain elemental links may vary, but their presence is mandatory. Therefore, the importance of cytoplasm in the cell of both plants and animals is equally great.

The role of cytoplasm in the cell

The importance of the cytoplasm in a cell is great, if not decisive. After all, this is the basis in which all vital structures are located, so it is difficult to overestimate its role. Several main points can be formulated that reveal this meaning.

1. It is she who unites all the components of the cell into one complex unified system that carries out life processes harmoniously and collectively.
2. Thanks to the water included in the composition, the cytoplasm in the cell functions as a medium for numerous complex biochemical interactions and physiological transformations of substances (glycolysis, nutrition, gas exchange).
3. This is the main “capacity” for the existence of all cell organelles.
4. Due to microfilaments and tubes, it forms a cytoskeleton, connecting organelles and allowing them to move.
5. It is in the cytoplasm that a number of enzymes are concentrated, without which not a single biochemical reaction occurs.

To summarize, we need to say the following. The role of the cytoplasm in the cell is practically key, since it is the basis of all processes, the living environment and the substrate for reactions.