Table of cell organelles and their functions. The structure of an animal cell

An organelle is a tiny cellular structure that performs specific functions inside. The organelles are embedded in the cytoplasm. In more complex eukaryotic cells, organelles are often surrounded by their own membrane. Like the internal organs of the body, organelles are specialized and perform specific functions necessary for the normal functioning of cells. They have a wide range of responsibilities, from generating energy to controlling cell growth and reproduction.

eukaryotic organelles

Eukaryotic cells are cells with a nucleus. The nucleus is an important organelle surrounded by a double membrane called the nuclear envelope that separates the contents of the nucleus from the rest of the cell. Eukaryotic cells also contain various cell organelles. Examples of eukaryotic organisms are animals, plants, and. and contain many of the same or different organelles. There are also some organelles found in plant cells that are not found in animal cells and vice versa. Examples of major organelles found in plant and animal cells include:

• - a structure associated with the membrane, which contains hereditary (DNA) information, and also controls the growth and reproduction of the cell. It is usually the most important organelle in the cell.
• , as energy producers, convert energy into forms that the cell can use. They are also involved in other processes such as division, growth, and.
• - an extensive network of tubules and pockets that synthesizes membranes, secretory proteins, carbohydrates, lipids and hormones.
• - a structure that is responsible for the production, storage and delivery of certain cellular substances, especially from the endoplasmic reticulum.
• - organelles consisting of RNA and proteins and are responsible for protein synthesis. Ribosomes are located in the cytosol or associated with the endoplasmic reticulum.
• - these membrane sacs of enzymes process organic material cells by digesting cellular macromolecules such as nucleic acids, polysaccharides, fats and proteins.
• , like lysosomes are connected by a membrane and contain enzymes. They help detoxify alcohol, form bile acids, and break down fats.
• are fluid-filled, closed structures most commonly found in plant cells and fungi. They are responsible for wide range important functions, including storage nutrients, detoxification and waste disposal.
• - plastids contained in plant cells, but absent in animal cells. Chloroplasts absorb energy sunlight for .
• - a rigid outer wall located near the plasma membrane in most plant cells, providing support and protection to the cell.
• - cylindrical structures are found in animal cells and help organize the assembly of microtubules during.
• - hair-like formations on the outside of some cells that carry out cellular locomotion. They are made up of specialized groups of microtubules called basal bodies.

prokaryotic cells

Prokaryotic cells have a structure that is less complex than that of eukaryotic cells. They do not have a nucleus where the DNA is bound by a membrane. Prokaryotic DNA is found in a region of the cytoplasm called the nucleoid. Like eukaryotic cells, prokaryotic cells have a plasma membrane, cell wall, and cytoplasm. Unlike eukaryotes, prokaryotes do not contain membrane-bound organelles. However, they have some non-membranous organelles such as ribosomes, flagella, and plasmids (circular structures of DNA that are not involved in reproduction). Examples of prokaryotic cells are and.

Organelles – permanent and mandatory components of cells; specialized sections of the cytoplasm of a cell that have a specific structure and perform specific functions in the cell. Distinguish between organelles of general and special purpose.

General purpose organelles are present in most cells (endoplasmic reticulum, mitochondria, plastids, Golgi complex, lysosomes, vacuoles, cell center, ribosomes). Special purpose organelles are characteristic only of specialized cells (myofibrils, flagella, cilia, contractile and digestive vacuoles). Organelles (with the exception of ribosomes and the cell center) have a membrane structure.

Endoplasmic reticulum(EPR) – this is a branched system of interconnected cavities, tubules and channels formed by elementary membranes and penetrating the entire thickness of the cell. Opened in 1943 by Porter. There are especially many channels of the endoplasmic reticulum in cells with intensive metabolism. On average, the volume of EPS is from 30% to 50% of the total cell volume. EPS is labile. Form of internal lacunae and cana

catches, their size, location in the cell and number change in the process of life. The cell is more developed in animals. EPS is morphologically and functionally connected with the boundary layer of the cytoplasm, the nuclear membrane, ribosomes, the Golgi complex, vacuoles, forming together with them a single functional and structural system for the metabolism and energy and movement of substances inside the cell. Mitochondria and plastids accumulate near the endoplasmic reticulum.

There are two types of EPS: rough and smooth. On the membranes of the smooth (agranular) ER, enzymes of the fat and carbohydrate synthesis systems are localized: carbohydrates and almost all cellular lipids are synthesized here. Membranes of a smooth variety of the endoplasmic reticulum predominate in cells sebaceous glands, liver (glycogen synthesis), in cells with a high content of nutrients (plant seeds). Ribosomes are located on the membrane of the rough (granular) EPS, where protein biosynthesis takes place. Some of the proteins synthesized by them are included in the membrane of the endoplasmic reticulum, the rest enter the lumen of its channels, where they are converted and transported to the Golgi complex. Especially a lot of rough membranes in the cells of the glands and nerve cells.

Rice. Rough and smooth endoplasmic reticulum.

Rice. Transport of substances through the system nucleus - endoplasmic reticulum (EPR) - Golgi complex.

Functions of the endoplasmic reticulum:

1) synthesis of proteins (rough ER), carbohydrates and lipids (smooth ER);

2) transport of substances, both entering the cell and newly synthesized;

3) division of the cytoplasm into compartments (compartments), which ensures the spatial separation of enzyme systems necessary for their sequential entry into biochemical reactions.

Mitochondria - are present in almost all types of cells single and multicellular organisms(with the exception of mammalian erythrocytes). Their number in different cells varies and depends on the level of functional activity of the cell. In a rat liver cell, there are about 2500 of them, and in the male reproductive cell of some mollusks - 20 - 22. There are more of them in pectoral muscle flying birds than in the pectoral muscle of non-flying birds.

Mitochondria are shaped like spherical, oval and cylindrical bodies. The sizes are 0.2 - 1.0 microns in diameter and up to 5 - 7 microns in length.

Rice. Mitochondria.

The length of filamentous forms reaches 15-20 microns. Outside, mitochondria are bounded by a smooth outer membrane, similar in composition to the plasmalemma. The inner membrane forms numerous outgrowths - cristae - and contains numerous enzymes, ATP-somes (mushroom bodies), involved in the transformation of nutrient energy into ATP energy. The number of cristae depends on the function of the cell. There are a lot of cristae in mitochondria; they occupy the entire internal cavity of the organoid. In mitochondria of embryonic cells, cristae are single. In plants, outgrowths of the inner membrane are more often tubular. The mitochondrial cavity is filled with a matrix that contains water, mineral salts, enzyme proteins, and amino acids. Mitochondria have an autonomous protein-synthesizing system: a circular DNA molecule, different kinds RNA and smaller ribosomes than in the cytoplasm.

Mitochondria are closely connected by membranes of the endoplasmic reticulum, whose channels often open directly into the mitochondria. With an increase in the load on the organ and intensification of synthetic processes that require energy expenditure, the contacts between EPS and mitochondria become especially numerous. The number of mitochondria can rapidly increase by fission. The ability of mitochondria to reproduce is due to the presence of a DNA molecule in them, resembling the circular chromosome of bacteria.

Mitochondrial Functions:

1) synthesis of a universal energy source - ATP;

2) synthesis of steroid hormones;

3) biosynthesis of specific proteins.

plastids - organelles of a membrane structure, characteristic only for plant cells. They are involved in the synthesis of carbohydrates, proteins and fats. According to the content of pigments, they are divided into three groups: chloroplasts, chromoplasts and leukoplasts.

Chloroplasts have a relatively constant elliptical or lenticular shape. The size of the largest diameter is 4 - 10 microns. The number in a cell ranges from a few units to several tens. Their size, color intensity, number and location in the cell depend on the lighting conditions, the type and physiological state of the plants.

Rice. Chloroplast, structure.

These are protein-lipoid bodies, consisting of 35-55% protein, 20-30% lipids, 9% chlorophyll, 4-5% carotenoids, 2-4% nucleic acids. The amount of carbohydrates varies; a certain amount of mineral substances Chlorophyll was found - an ester of an organic dibasic acid - chlorophyllin and organic alcohols - methyl (CH 3 OH) and phytol (C 20 H 39 OH). In higher plants, chlorophyll a is constantly present in chloroplasts - has a blue-green color, and chlorophyll b - yellow-green; and the content of chlorophyll, and several times more.

In addition to chlorophyll, chloroplasts contain pigments - carotene C 40 H 56 and xanthophyll C 40 H 56 O 2 and some other pigments (carotenoids). In a green leaf, the yellow satellites of chlorophyll are masked by a brighter green color. However, in autumn, during leaf fall, in most plants, chlorophyll is destroyed and then the presence of carotenoids in the leaf is detected - the leaf turns yellow.

The chloroplast is surrounded by a double membrane consisting of an outer and an inner membrane. The internal contents - the stroma - has a lamellar (lamellar) structure. In the colorless stroma, grana are isolated - green-colored bodies, 0.3 - 1.7 microns. They are a collection of thylakoids - closed bodies in the form of flat vesicles or discs of membrane origin. Chlorophyll in the form of a monomolecular layer is located between the protein and lipid layers in close connection with them. The spatial arrangement of pigment molecules in the membrane structures of chloroplasts is highly expedient and creates optimal conditions for the most efficient absorption, transmission and use of radiant energy. Lipids form anhydrous dielectric layers of chloroplast membranes necessary for the functioning of the electron transport chain. The role of links in the electron transport chain is performed by proteins (cytochromes, plastoquinones, ferredoxin, plastocyanin) and individual chemical elements- iron, manganese, etc. The number of grains in the chloroplast is from 20 to 200. Stroma lamellae are located between the grains, connecting them with each other. The gran lamellae and stroma lamellae have a membranous structure.

The internal structure of the chloroplast makes possible the spatial dissociation of numerous and varied reactions, which in their totality constitute the content of photosynthesis.

Chloroplasts, like mitochondria, contain specific RNA and DNA, as well as smaller ribosomes and the entire molecular arsenal necessary for protein biosynthesis. These organelles have a sufficient amount of i-RNA to ensure the maximum activity of the protein-synthesizing system. However, they also contain enough DNA to encode certain proteins. They reproduce by division, by simple constriction.

It has been established that chloroplasts can change their shape, size and position in the cell, that is, they are able to move independently (chloroplast taxis). They found two types of contractile proteins, due to which, obviously, the active movement of these organelles in the cytoplasm is carried out.

Chromoplasts are widely distributed in the generative organs of plants. They color the petals of flowers (buttercup, dahlia, sunflower), fruits (tomatoes, mountain ash, wild rose) in yellow, orange, red. In vegetative organs, chromoplasts are much less common.

The color of chromoplasts is due to the presence of carotenoids - carotene, xanthophyll and lycopene, which are in plastids in a different state: in the form of crystals, a lipoid solution, or in combination with proteins.

Chromoplasts, in comparison with chloroplasts, have a simpler structure - they lack a lamellar structure. Chemical composition also excellent: pigments - 20-50%, lipids up to 50%, proteins - about 20%, RNA - 2-3%. This indicates a lower physiological activity of chloroplasts.

Leucoplasts do not contain pigments, they are colorless. These smallest plastids are round, ovoid or rod-shaped. In the cell, they often cluster around the nucleus.

Internally, the structure is even less differentiated compared to chloroplasts. They synthesize starch, fats, proteins. In accordance with this, three types of leukoplasts are distinguished - amyloplasts (starch), oleoplasts (vegetable oils) and proteoplasts (proteins).

Leukoplasts arise from proplastids, with which they are similar in shape and structure, but differ only in size.

All plastids are genetically related to each other. They are formed from proplastids - the smallest colorless cytoplasmic formations similar in appearance with mitochondria. Proplastids are found in spores, eggs, in embryonic cells of growth points. Chloroplasts (in the light) and leukoplasts (in the dark) are formed directly from proplastids, and chromoplasts develop from them, which are the end product in the evolution of plastids in the cell.

Golgi complex - was first discovered in 1898 by the Italian scientist Golgi in animal cells. This is a system of internal cavities, cisterns (5-20), located close and parallel to each other, and large and small vacuoles. All these formations have a membrane structure and are specialized sections of the endoplasmic reticulum. In animal cells, the Golgi complex is better developed than in plant cells; in the latter it is called dictyosomes.

Rice. The structure of the Golgi complex.

Proteins and lipids entering the lamellar complex are subjected to various transformations, accumulated, sorted, packaged in secretory vesicles and transported according to their destination: to various structures inside the cell or outside the cell. The membranes of the Golgi complex also synthesize polysaccharides and form lysosomes. In the cells of the mammary glands, the Golgi complex is involved in the formation of milk, and in the cells of the liver - bile.

Functions of the Golgi complex:

1) concentration, dehydration and compaction of proteins synthesized in the cell, fats, polysaccharides and substances that came from outside;

2) the assembly of complex complexes of organic substances and their preparation for removal from the cell (cellulose and hemicellulose in plants, glycoproteins and glycolipids in animals);

3) synthesis of polysaccharides;

4) formation of primary lysosomes.

Lysosomes - small oval bodies with a diameter of 0.2-2.0 microns. The central position is occupied by a vacuole containing 40 (according to various sources 30-60) hydrolytic enzymes capable of acidic environment(pH 4.5-5) to break down proteins, nucleic acids, polysaccharides, lipids and other substances.

Around this cavity there is a stroma, dressed on the outside with an elementary membrane. The breakdown of substances with the help of enzymes is called lysis, so the organelle is called a lysosome. Lysosomes are formed in the Golgi complex. Primary lysosomes approach directly pinocytic or phagocytic vacuoles (endosomes) and pour their contents into their cavity, forming secondary lysosomes (phagosomes), inside which digestion of substances occurs. The products of lysis through the membrane of lysosomes enter the cytoplasm and are included in further metabolism. Secondary lysosomes with remnants of undigested substances are called residual bodies. An example of secondary lysosomes are the digestive vacuoles of protozoa.

Functions of lysosomes:

1) intracellular digestion of food macromolecules and foreign components entering the cell during pino- and phagocytosis, providing the cell with additional raw materials for biochemical and energy processes;

2) during starvation, lysosomes digest some organelles and replenish the supply of nutrients for a while;

3) destruction of temporary organs of embryos and larvae (tail and gills in a frog) in the process postembryonic development;

Rice. Lysosome formation

Vacuoles – fluid-filled cavities in the cytoplasm of plant cells and protists. They have the form of bubbles, thin tubules and another. Vacuoles are formed from extensions of the endoplasmic reticulum and vesicles of the Golgi complex as the thinnest cavities, then, as the cell grows and the accumulation of metabolic products, their volume increases and the number decreases. A developed, formed cell usually has one large vacuole, which occupies a central position.

The vacuoles of plant cells are filled with cell sap, which is water solution organic (malic, oxalic, citric acids, sugars, inulin, amino acids, proteins, tannins, alkaloids, glucosides) and mineral (nitrates, chlorides, phosphates) substances.

Protists have digestive and contractile vacuoles.

Functions of vacuoles:

1) storage of reserve nutrients and receptacles for excretions (in plants);

2) determine and maintain osmotic pressure in cells;

3) provide intracellular digestion in protists.

Rice. Cell center.

Cell Center usually located near the nucleus and consists of two centrioles located perpendicular to each other and surrounded by a radiant sphere. Each centriole is a hollow cylindrical body 0.3-0.5 µm long and 0.15 µm long, the wall of which is formed by 9 triplets of microtubules. If the centriole lies at the base of the cilium or flagellum, then it is called basal body.

Before dividing, the centrioles diverge to opposite poles, and a daughter centriole appears near each of them. From centrioles located at different poles of the cell, microtubules are formed that grow towards each other. They form a mitotic spindle, which contributes to the uniform distribution of genetic material between daughter cells, and are the center of the organization of the cytoskeleton. Part of the spindle threads is attached to the chromosomes. In the cells of higher plants, the cell center does not have centrioles.

Centrioles are self-reproducing organelles of the cytoplasm. They arise as a result of duplication of existing ones. This happens when the centrioles diverge. The immature centriole contains 9 single microtubules; apparently, each microtubule is a template for the assembly of triplets characteristic of a mature centriole.

The centrosome is characteristic of animal cells, some fungi, algae, mosses, and ferns.

Functions of the cell center:

1) the formation of fission poles and the formation of fission spindle microtubules.

Ribosomes - small spherical organelles, from 15 to 35 nm. Consist of two subunits large (60S) and small (40S). They contain about 60% protein and 40% ribosomal RNA. rRNA molecules form its structural framework. Most proteins are specifically associated with certain regions of rRNA. Some proteins are only incorporated into ribosomes during protein synthesis. Ribosome subunits are formed in the nucleolus. and through the pores in the nuclear membrane enter the cytoplasm, where they are located either on the EPA membrane, or on the outer side of the nuclear membrane, or freely in the cytoplasm. First, rRNAs are synthesized on nucleolar DNA, which are then covered with ribosomal proteins coming from the cytoplasm, cleaved to the desired size, and form ribosome subunits. There are no fully formed ribosomes in the nucleus. The association of subunits into a whole ribosome occurs in the cytoplasm, as a rule, during protein biosynthesis. Compared with mitochondria, plastids, prokaryotic cells, ribosomes in the cytoplasm of eukaryotic cells are larger. They can combine 5-70 units into polysomes.

Ribosome functions:

1) participation in protein biosynthesis.

Rice. 287. Ribosome: 1 - small subunit; 2 - large subunit.

Cilia, flagella – outgrowths of the cytoplasm covered with an elementary membrane, under which there are 20 microtubules, forming 9 pairs along the periphery and two single ones in the center. At the base of the cilia and flagella are the basal bodies. The flagella are up to 100 µm long. Cilia are short - 10-20 microns - flagella. The movement of the flagella is helical, and that of the cilia is paddle-like. Thanks to cilia and flagella, bacteria, protists, ciliary cells move, particles or liquids move (cilia of the ciliated epithelium respiratory tract, oviducts), sex cells (spermatozoa).

Rice. The structure of flagella and cilia in eukaryotes

Inclusions - temporary components of the cytoplasm, either arising or disappearing. As a rule, they are contained in cells at certain stages life cycle. The specificity of inclusions depends on the specificity of the corresponding cells of tissues and organs. Inclusions are found predominantly in plant cells. They can occur in the hyaloplasm, various organelles, less often in the cell wall.

In functional terms, inclusions are either compounds temporarily removed from the metabolism of cells (reserve substances - starch grains, lipid drops and protein deposits), or end products of metabolism (crystals of certain substances).

starch grains. These are the most common plant cell inclusions. Starch is stored in plants exclusively in the form of starch grains. They are formed only in the plastid stroma of living cells. During photosynthesis, green leaves produce assimilation, or primary starch. Assimilation starch does not accumulate in the leaves and, rapidly hydrolyzing to sugars, flows into the parts of the plant in which it accumulates. There it turns back into starch, which is called secondary. Secondary starch is also formed directly in tubers, rhizomes, seeds, that is, where it is deposited in stock. Then they call him spare. Leukoplasts that store starch are called amyloplasts. Especially rich in starch are seeds, underground shoots (tubers, bulbs, rhizomes), parenchyma of conductive tissues of roots and stems of woody plants.

Lipid drops. Found in almost all plant cells. The seeds and fruits are richest in them. Fatty oils in the form of lipid droplets are the second most important (after starch) form of reserve nutrients. Seeds of some plants (sunflower, cotton, etc.) can accumulate up to 40% of oil by weight of dry matter.

Lipid drops, as a rule, accumulate directly in the hyaloplasm. They are spherical bodies usually of submicroscopic size. Lipid droplets can also accumulate in leukoplasts, which are called elaioplasts.

Protein inclusions are formed in various organelles of the cell in the form of amorphous or crystalline deposits of various shapes and structures. Most often, crystals can be found in the nucleus - in the nucleoplasm, sometimes in the perinuclear space, less often in the hyaloplasm, plastid stroma, in the extensions of the EPR tanks, the matrix of peroxisomes and mitochondria. Vacuoles contain both crystalline and amorphous protein inclusions. AT most protein crystals are found in the storage cells of dry seeds in the form of so-called aleuronic 3 grains or protein bodies.

Storage proteins are synthesized by ribosomes during seed development and deposited in vacuoles. When the seeds ripen, accompanied by their dehydration, the protein vacuoles dry out and the protein crystallizes. As a result, in a mature dry seed, protein vacuoles turn into protein bodies (aleurone grains).

Lesson type: combined.

Methods: verbal, visual, practical, problem-search.

Lesson Objectives

Educational: to deepen students' knowledge of the structure of eukaryotic cells, to teach how to apply them in practical classes.

Developing: improve students' skills to work with didactic material; develop students' thinking by offering tasks for comparing prokaryotic and eukaryotic cells, plant cells and animal cells with the identification of similar and distinctive features.

Equipment: poster "The structure of the cytoplasmic membrane"; task cards; handout (the structure of a prokaryotic cell, a typical plant cell, the structure of an animal cell).

Intersubject communications: botany, zoology, human anatomy and physiology.

Lesson plan

I. Organizational moment

Check readiness for the lesson.
Checking the list of students.
Presentation of the topic and objectives of the lesson.

II. Learning new material

Division of organisms into pro- and eukaryotes

The shape of the cells is extremely diverse: some are rounded, others look like stars with many rays, others are elongated, etc. Cells are also different in size - from the smallest, hardly distinguishable in a light microscope, to those perfectly visible to the naked eye (for example, fish and frog eggs).

Any unfertilized egg, including giant fossilized dinosaur eggs that are kept in paleontological museums, were also once living cells. However, if we talk about the main elements internal structure all cells are similar.

prokaryotes (from lat. pro- before, before, instead of and Greek. karyon- nucleus) - these are organisms whose cells do not have a nucleus limited by a membrane, i.e. all bacteria, including archaebacteria and cyanobacteria. Total number there are about 6000 prokaryotic species. All the genetic information of a prokaryotic cell (genophore) is contained in a single circular DNA molecule. Mitochondria and chloroplasts are absent, and the functions of respiration or photosynthesis, which provide the cell with energy, are performed by the plasma membrane (Fig. 1). Prokaryotes reproduce without a pronounced sexual process by dividing in two. Prokaryotes are able to carry out a number of specific physiological processes: they fix molecular nitrogen, carry out lactic acid fermentation, decompose wood, and oxidize sulfur and iron.

After an introductory conversation, students consider the structure of a prokaryotic cell, comparing the main features of the structure with the types of eukaryotic cells (Fig. 1).

eukaryotes - These are higher organisms that have a clearly defined nucleus, which is separated from the cytoplasm by a membrane (karyomembrane). Eukaryotes include all higher animals and plants, as well as unicellular and multicellular algae, fungi and protozoa. Nuclear DNA in eukaryotes is enclosed in chromosomes. Eukaryotes have cellular organelles limited by membranes.

Differences between eukaryotes and prokaryotes

- Eukaryotes have a real nucleus: the genetic apparatus of a eukaryotic cell is protected by a shell similar to the shell of the cell itself.
– Organelles included in the cytoplasm are surrounded by a membrane.

The structure of plant and animal cells

The cell of any organism is a system. It consists of three interconnected parts: membrane, nucleus and cytoplasm.

In the study of botany, zoology and human anatomy, you have already become familiar with the structure various types cells. Let's briefly review this article.

Exercise 1. Determine from Figure 2 which organisms and tissue types correspond to the cells under the numbers 1-12. What is the reason for their shape?

The structure and functions of organelles of plant and animal cells

Using figures 3 and 4 and using the Biological encyclopedic dictionary and a textbook, students fill out a table comparing animal and plant cells.

Table. The structure and functions of organelles of plant and animal cells

conclusions

1. The cell wall, plastids and the central vacuole are inherent only in plant cells.
2. Lysosomes, centrioles, microvilli are present mainly only in the cells of animal organisms.
3. All other organelles are characteristic of both plant and animal cells.

The structure of the cell membrane

The cell membrane is located outside the cell, delimiting the latter from the external or internal environment of the body. It is based on the plasmalemma (cell membrane) and the carbohydrate-protein component.

Cell wall functions:

- maintains the shape of the cell and gives mechanical strength to the cell and the organism as a whole;
- protects the cell from mechanical damage and the ingress of harmful compounds into it;
- performs recognition of molecular signals;
- regulates the exchange of substances between the cell and the environment;
- carries out intercellular interaction in a multicellular organism.

Cell wall function:

- represents an external frame - a protective shell;
- provides transport of substances (water, salts, molecules of many organic substances pass through the cell wall).

The outer layer of animal cells, unlike the cell walls of plants, is very thin and elastic. It is not visible under a light microscope and consists of a variety of polysaccharides and proteins. The surface layer of animal cells is called glycocalyx, performs the function of a direct connection of animal cells with the external environment, with all the substances surrounding it, does not play a supporting role.

Under the glycocalyx of the animal and cell wall of the plant cell, there is a plasma membrane that borders directly on the cytoplasm. The plasma membrane contains proteins and lipids. They are arranged in an orderly manner due to various chemical interactions with each other. Lipid molecules in the plasma membrane are arranged in two rows and form a continuous lipid bilayer. Protein molecules do not form a continuous layer, they are located in the lipid layer, plunging into it at different depths. Molecules of proteins and lipids are mobile.

Functions of the plasma membrane:

- forms a barrier that separates the internal contents of the cell from external environment;
- provides transport of substances;
- provides communication between cells in the tissues of multicellular organisms.

Entry of substances into the cell

The surface of the cell is not continuous. In the cytoplasmic membrane there are numerous tiny holes - pores through which, with or without the help of special proteins, ions and small molecules can penetrate into the cell. In addition, some ions and small molecules can enter the cell directly through the membrane. The entry of the most important ions and molecules into the cell is not passive diffusion, but active transport, which requires energy. Transport of substances is selective. The selective permeability of the cell membrane is called semipermeability.

way phagocytosis inside the cell enter: large molecules of organic substances, such as proteins, polysaccharides, food particles, bacteria. Phagocytosis is carried out with the participation of the plasma membrane. In the place where the surface of the cell comes into contact with a particle of some dense substance, the membrane flexes, forms a recess and surrounds the particle, which in the "membrane capsule" is immersed inside the cell. A digestive vacuole is formed, and organic substances that have entered the cell are digested in it.

By phagocytosis, amoeba, ciliates, animal and human leukocytes feed. Leukocytes absorb bacteria, as well as a variety of solid particles that accidentally enter the body, thus protecting it from pathogenic bacteria. The cell wall of plants, bacteria and blue-green algae prevents phagocytosis, and therefore this pathway of substances entering the cell is not realized in them.

Liquid droplets containing various substances in a dissolved and suspended state also penetrate into the cell through the plasma membrane. This phenomenon was called pinocytosis. The process of fluid absorption is similar to phagocytosis. A drop of liquid is immersed in the cytoplasm in a "membrane package". organic matter, which entered the cell along with water, begin to be digested under the influence of enzymes contained in the cytoplasm. Pinocytosis is widespread in nature and is carried out by the cells of all animals.

III. Consolidation of the studied material

For which two large groups Are all organisms divided according to the structure of the nucleus?
What organelles are found only in plant cells?
What organelles are found only in animal cells?
What is the difference between the structure of the cell wall of plants and animals?
What are the two ways substances enter the cell?
What is the importance of phagocytosis for animals?

1. Consider Figure 24 on p. 54-55 textbook. Remember the names, location and features of the functioning of organelles.

2. Fill in the cluster "Basic components of a eukaryotic cell".

3. On the basis of what main features is a cell considered eukaryotic?
Eukaryotic cells have a well-formed nucleus. Eukaryotic cells are large and complex compared to prokaryotic cells.

4. Sketch the structure of the cell membrane and label its elements.

5. Sign the animal and plant cells in the figure and designate their main organelles.

6. Fill in the cluster “Main functions of the outer cell membrane”.
Membrane functions:
Barrier
Transport
Cell interaction with environment and other cells.

7. Compose a syncwine for the term "membrane".
Membrane.
Selectively permeable, two-layer.
Transports, protects, signals.
Elastic molecular structure composed of proteins and lipids.
Shell.

8. Why are the phenomena of phagocytosis and pinocytosis very common in animal cells and practically absent in plant cells and fungal cells?
Plant and fungal cells have a cell wall that animals do not have. This allows the cytoplasmic membrane to absorb water with mineral salts (pinocytosis) due to greater elasticity. Due to this property, the process of phagocytosis is also carried out - the capture of solid particles.

9. Fill in the cluster "Organoids of eukaryotic cells".
Organelles: membranous and non-membrane.
Membrane: single-membrane and double-membrane.

10. Establish a correspondence between groups and individual organelles.
Organelles
1. Mitochondria
2. EPS
3. Cell center
4. Vacuole
5. Golgi apparatus
6. Lysosomes
7. Ribosomes
8. Plastids
Groups
A. Single membrane
B. Double membrane
B. Non-membrane

11. Fill in the table.

The structure and functions of cell organelles

12. Fill in the table.

COMPARATIVE CHARACTERISTICS OF PLANT AND ANIMAL CELLS

13. Choose the name of any organoid and make three types of sentences with this term: narrative, interrogative, exclamatory.
A vacuole is a large membranous vesicle filled with cell sap.
The vacuole is an essential part of the plant cell!
What functions, besides the accumulation of reserve substances, does the vacuole perform?

14. Give definitions of concepts.
Inclusions- These are optional components of the cell, appearing and disappearing depending on the intensity and nature of the metabolism in the cell and on the conditions of existence of the organism.
Organelles- permanent specialized structures in the cells of living organisms.

15. Choose the correct answer.
Test 1
Responsible for the formation of lysosomes, accumulation, modification and removal of substances from the cell:
2) Golgi complex;

Test 2
The hydrophobic base of the cell membrane is:
3) phospholipids;

Test 3
Single-membrane cell organelles:
2) lysosomes;

16. Explain the origin and general meaning word (term), based on the meaning of the roots that make it up.

17. Choose a term and explain how its modern meaning corresponds to the original meaning of its roots.
The chosen term is exocytosis.
Correspondence, the term corresponds, but the mechanism has become clear and refined. it cellular process, at which membrane vesicles merge with the outer cell membrane. During exocytosis, the contents of the secretory vesicles are released to the outside, and their membrane merges with the cell membrane.

18. Formulate and write down the main ideas of § 2.7.
The cell consists of three main components: the nucleus, the cytoplasm and the cell membrane.
In the cytoplasm there are organelles, inclusions and hyaloplasm (the main substance). Organelles are single-membrane (ER, Golgi complex, lysosomes, etc.), two-membrane (mitochondria, plastids) and non-membrane (ribosomes, cell center). A plant cell differs from an animal cell in that it has additional structures: a vacuole, plastids, a cell wall, and there are no centrioles in the cell center. All organelles and components of the cell make up a well-coordinated complex that works as a whole.

The cell organelles persistent cellular organs, structures that ensure the implementation of a number of functions in the process of cell life: the preservation and transmission of genetic information, movement, division, transfer of substances, synthesis, and others.

To eukaryotic cell organelles includes:

• chromosomes;
• ribosomes;
• mitochondria;
• cell membrane;
• microfilaments;
• microtubules;
• Golgi complex;
• endoplasmic reticulum;
• lysosomes.

The nucleus is also usually referred to as an organelle of eukaryotic cells. The main feature of a plant cell is the presence of plastids.

The structure of a plant cell:

Typically, a plant cell includes:

• membrane;
• cytoplasm with organelles;
• cellulose casing;
• vacuoles with cell sap;
• nucleus.

The structure of an animal cell:

The structure of an animal cell consists of:

What is the function of cellular organelles - table

Cellular organelles - video