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Organelles- permanent, necessarily present, components of the cell that perform specific functions.

Endoplasmic reticulum

Endoplasmic reticulum (ER), or endoplasmic reticulum (EPR), is a single-membrane organelle. It is a system of membranes that form "tanks" and channels, connected to each other and limiting a single internal space - EPS cavities. On the one hand, the membranes are connected to the cytoplasmic membrane, on the other hand, to the outer nuclear membrane. There are two types of EPS: 1) rough (granular), containing ribosomes on its surface, and 2) smooth (agranular), the membranes of which do not carry ribosomes.

Functions: 1) transport of substances from one part of the cell to another, 2) division of the cytoplasm of the cell into compartments ("compartments"), 3) synthesis of carbohydrates and lipids (smooth ER), 4) protein synthesis (rough ER), 5) place of formation of the Golgi apparatus .

Or golgi complex, is a single-membrane organelle. It is a stack of flattened "tanks" with widened edges. A system of small single-membrane vesicles (Golgi vesicles) is associated with them. Each stack usually consists of 4-6 "tanks", is a structural and functional unit of the Golgi apparatus and is called a dictyosome. The number of dictyosomes in a cell ranges from one to several hundred. In plant cells, dictyosomes are isolated.

The Golgi apparatus is usually located near the cell nucleus (in animal cells often near the cell center).

Functions of the Golgi apparatus: 1) accumulation of proteins, lipids, carbohydrates, 2) modification of incoming organic substances, 3) "packaging" of proteins, lipids, carbohydrates into membrane vesicles, 4) secretion of proteins, lipids, carbohydrates, 5) synthesis of carbohydrates and lipids, 6) place of formation lysosomes. The secretory function is the most important, therefore the Golgi apparatus is well developed in the secretory cells.

Lysosomes

Lysosomes- single-membrane organelles. They are small bubbles (diameter from 0.2 to 0.8 microns) containing a set of hydrolytic enzymes. Enzymes are synthesized on the rough ER, move to the Golgi apparatus, where they are modified and packaged into membrane vesicles, which, after separation from the Golgi apparatus, become lysosomes proper. A lysosome can contain from 20 to 60 various kinds hydrolytic enzymes. The breakdown of substances by enzymes is called lysis.

Distinguish: 1) primary lysosomes, 2) secondary lysosomes. Primary lysosomes are called lysosomes, detached from the Golgi apparatus. Primary lysosomes are a factor that ensures the exocytosis of enzymes from the cell.

Secondary lysosomes are called lysosomes, formed as a result of the fusion of primary lysosomes with endocytic vacuoles. In this case, they digest substances that have entered the cell by phagocytosis or pinocytosis, so they can be called digestive vacuoles.

Autophagy- the process of destruction of structures unnecessary to the cell. First, the structure to be destroyed is surrounded by a single membrane, then the formed membrane capsule merges with the primary lysosome, as a result, a secondary lysosome (autophagic vacuole) is also formed, in which this structure is digested. Digestion products are absorbed by the cytoplasm of the cell, but some of the material remains undigested. The secondary lysosome containing this undigested material is called the residual body. By exocytosis, undigested particles are removed from the cell.

Autolysis- self-destruction of the cell, resulting from the release of the contents of lysosomes. Normally, autolysis takes place during metamorphoses (disappearance of the tail of the frog tadpole), involution of the uterus after childbirth, in foci of tissue necrosis.

Functions of lysosomes: 1) intracellular digestion of organic substances, 2) destruction of unnecessary cellular and non-cellular structures, 3) participation in the processes of cell reorganization.

Vacuoles

Vacuoles- single-membrane organelles, are "capacities" filled with aqueous solutions organic and inorganic substances. The ER and the Golgi apparatus take part in the formation of vacuoles. Young plant cells contain many small vacuoles, which then, as the cells grow and differentiate, merge with each other and form one large central vacuole. The central vacuole can occupy up to 95% of the volume of a mature cell, while the nucleus and organelles are pushed back to the cell membrane. The membrane that surrounds the plant vacuole is called the tonoplast. The fluid that fills the plant vacuole is called cell sap. The composition of cell sap includes water-soluble organic and inorganic salts, monosaccharides, disaccharides, amino acids, end or toxic metabolic products (glycosides, alkaloids), some pigments (anthocyanins).

Animal cells contain small digestive and autophagic vacuoles that belong to the group of secondary lysosomes and contain hydrolytic enzymes. Unicellular animals also have contractile vacuoles that perform the function of osmoregulation and excretion.

Vacuole functions: 1) accumulation and storage of water, 2) regulation of water-salt metabolism, 3) maintenance of turgor pressure, 4) accumulation of water-soluble metabolites, reserve nutrients, 5) coloring of flowers and fruits and thereby attracting pollinators and seed dispersers, 6) see. lysosome functions.

Endoplasmic reticulum, Golgi apparatus, lysosomes and vacuoles form single vacuolar network of the cell, whose individual elements can transform into each other.

Mitochondria

1 - outer membrane;
2 - inner membrane; 3 - matrix; 4 - crista; 5 - multienzyme system; 6 - circular DNA.

The shape, size, and number of mitochondria are extremely variable. The shape of the mitochondria can be rod-shaped, round, spiral, cup-shaped, branched. The length of mitochondria ranges from 1.5 to 10 µm, the diameter is from 0.25 to 1.00 µm. The number of mitochondria in a cell can reach several thousand and depends on metabolic activity cells.

Mitochondria are bounded by two membranes. outer membrane mitochondria (1) smooth, internal (2) forms numerous folds - cristae(four). Cristae increase the surface area of ​​the inner membrane, which hosts multienzyme systems (5) involved in the synthesis of ATP molecules. The inner space of mitochondria is filled with matrix (3). The matrix contains circular DNA (6), specific mRNA, prokaryotic-type ribosomes (70S-type), Krebs cycle enzymes.

Mitochondrial DNA is not associated with proteins ("naked"), is attached to the inner membrane of the mitochondria and carries information about the structure of about 30 proteins. Many more proteins are required to build a mitochondrion, so information about most mitochondrial proteins is contained in nuclear DNA, and these proteins are synthesized in the cytoplasm of the cell. Mitochondria are able to reproduce autonomously by dividing in two. Between the outer and inner membranes is proton reservoir, where the accumulation of H + occurs.

Mitochondrial functions: 1) ATP synthesis, 2) oxygen breakdown of organic substances.

According to one of the hypotheses (the theory of symbiogenesis), mitochondria originated from ancient free-living aerobic prokaryotic organisms, which, having accidentally entered the host cell, then formed a mutually beneficial symbiotic complex with it. The following data support this hypothesis. First, mitochondrial DNA has the same structural features as the DNA of modern bacteria (closed in a ring, not associated with proteins). Second, mitochondrial ribosomes and bacterial ribosomes belong to the same type, the 70S type. Thirdly, the mechanism of mitochondrial division is similar to that of bacteria. Fourth, the synthesis of mitochondrial and bacterial proteins is inhibited by the same antibiotics.

plastids

1 - outer membrane; 2 - inner membrane; 3 - stroma; 4 - thylakoid; 5 - grana; 6 - lamellae; 7 - grains of starch; 8 - lipid drops.

Plastids are found only in plant cells. Distinguish three main types of plastids: leukoplasts are colorless plastids in the cells of unstained parts of plants, chromoplasts are colored plastids, usually yellow, red and orange, chloroplasts are green plastids.

Chloroplasts. In the cells of higher plants, chloroplasts have the shape of a biconvex lens. The length of chloroplasts ranges from 5 to 10 microns, the diameter is from 2 to 4 microns. Chloroplasts are bounded by two membranes. The outer membrane (1) is smooth, the inner (2) has a complex folded structure. The smallest fold is called thylakoid(four). A group of thylakoids stacked like a stack of coins is called faceted(5). The chloroplast contains an average of 40-60 grains arranged in a checkerboard pattern. The granules are connected to each other by flattened channels - lamellae(6). The thylakoid membranes contain photosynthetic pigments and enzymes that provide ATP synthesis. The main photosynthetic pigment is chlorophyll, which determines the green color of chloroplasts.

The inner space of chloroplasts is filled stroma(3). The stroma contains circular naked DNA, 70S-type ribosomes, Calvin cycle enzymes, and starch grains (7). Inside each thylakoid there is a proton reservoir, H + accumulates. Chloroplasts, like mitochondria, are capable of autonomous reproduction by dividing in two. They are found in the cells of the green parts of higher plants, especially many chloroplasts in leaves and green fruits. The chloroplasts of lower plants are called chromatophores.

Function of chloroplasts: photosynthesis. It is believed that chloroplasts originated from ancient endosymbiotic cyanobacteria (symbiogenesis theory). The basis for this assumption is the similarity of chloroplasts and modern bacteria in a number of ways (circular, "naked" DNA, 70S-type ribosomes, mode of reproduction).

Leukoplasts. The shape varies (spherical, rounded, cupped, etc.). Leucoplasts are bounded by two membranes. The outer membrane is smooth, the inner one forms small thylakoids. The stroma contains circular "naked" DNA, 70S-type ribosomes, enzymes for the synthesis and hydrolysis of reserve nutrients. There are no pigments. Especially many leukoplasts have cells of the underground organs of the plant (roots, tubers, rhizomes, etc.). Function of leukoplasts: synthesis, accumulation and storage of reserve nutrients. Amyloplasts- leukoplasts that synthesize and accumulate starch, elaioplasts- oils, proteinoplasts- squirrels. Different substances can accumulate in the same leukoplast.

Chromoplasts. Limited by two membranes. The outer membrane is smooth, the inner or also smooth, or forms single thylakoids. The stroma contains circular DNA and pigments - carotenoids, which give the chromoplasts a yellow, red or orange color. The form of accumulation of pigments is different: in the form of crystals, dissolved in lipid drops (8), etc. They are contained in the cells of mature fruits, petals, autumn leaves, rarely - root crops. Chromoplasts are considered the final stage of plastid development.

Function of chromoplasts: coloring of flowers and fruits and thereby attracting pollinators and seed dispersers.

All types of plastids can be formed from proplastids. proplastids- small organelles contained in meristematic tissues. Since plastids have a common origin, interconversions are possible between them. Leukoplasts can turn into chloroplasts (greening of potato tubers in the light), chloroplasts - into chromoplasts (yellowing of leaves and reddening of fruits). The transformation of chromoplasts into leukoplasts or chloroplasts is considered impossible.

Ribosomes

1 - large subunit; 2 - small subunit.

Ribosomes- non-membrane organelles, about 20 nm in diameter. Ribosomes consist of two subunits, large and small, into which they can dissociate. Chemical composition ribosomes are proteins and rRNA. rRNA molecules make up 50-63% of the mass of the ribosome and form its structural framework. There are two types of ribosomes: 1) eukaryotic (with sedimentation constants of the whole ribosome - 80S, small subunit - 40S, large - 60S) and 2) prokaryotic (respectively 70S, 30S, 50S).

Eukaryotic type ribosomes contain 4 rRNA molecules and about 100 protein molecules, while prokaryotic type ribosomes contain 3 rRNA molecules and about 55 protein molecules. During protein biosynthesis, ribosomes can “work” singly or combine into complexes - polyribosomes (polysomes). In such complexes, they are linked to each other by a single mRNA molecule. Prokaryotic cells have only 70S-type ribosomes. Eukaryotic cells have both 80S-type ribosomes (rough ER membranes, cytoplasm) and 70S-type ribosomes (mitochondria, chloroplasts).

Eukaryotic ribosome subunits are formed in the nucleolus. The association of subunits into a whole ribosome occurs in the cytoplasm, as a rule, during protein biosynthesis.

Ribosome function: assembly of the polypeptide chain (protein synthesis).

cytoskeleton

cytoskeleton made up of microtubules and microfilaments. Microtubules are cylindrical unbranched structures. The length of microtubules ranges from 100 µm to 1 mm, the diameter is approximately 24 nm, and the wall thickness is 5 nm. The main chemical component is the protein tubulin. Microtubules are destroyed by colchicine. Microfilaments - threads with a diameter of 5-7 nm, consist of actin protein. Microtubules and microfilaments form complex tangles in the cytoplasm. Functions of the cytoskeleton: 1) determination of the shape of the cell, 2) support for organelles, 3) formation of a division spindle, 4) participation in cell movements, 5) organization of the flow of the cytoplasm.

Includes two centrioles and a centrosphere. Centriole is a cylinder, the wall of which is formed by nine groups of three fused microtubules (9 triplets), interconnected at certain intervals by cross-links. Centrioles are paired, where they are located at right angles to each other. Before cell division, centrioles diverge to opposite poles, and a daughter centriole appears near each of them. They form a spindle of division, which contributes to the uniform distribution of genetic material between daughter cells. In the cells of higher plants (gymnosperms, angiosperms), the cell center does not have centrioles. Centrioles are self-reproducing organelles of the cytoplasm, they arise as a result of duplication of already existing centrioles. Functions: 1) ensuring the divergence of chromosomes to the poles of the cell during mitosis or meiosis, 2) the center of organization of the cytoskeleton.

Organelles of movement

They are not present in all cells. The organelles of movement include cilia (ciliates, epithelium respiratory tract), flagella (flagellates, spermatozoa), pseudopods (rhizomes, leukocytes), myofibrils (muscle cells), etc.

Flagella and cilia- organelles of a filamentous form, represent an axoneme bounded by a membrane. Axoneme - cylindrical structure; the wall of the cylinder is formed by nine pairs of microtubules, in its center there are two single microtubules. At the base of the axoneme there are basal bodies represented by two mutually perpendicular centrioles (each basal body consists of nine triplets of microtubules; there are no microtubules in its center). The length of the flagellum reaches 150 µm, the cilia are several times shorter.

myofibrils consist of actin and myosin myofilaments, which provide contraction of muscle cells.

Go to lectures number 6"Eukaryotic cell: cytoplasm, cell wall, structure and functions of cell membranes"

1) The main organelles of a plant cell classification and functions.

2) Leaf classification:

• simple - one leaf blade;
• complex - several leaf blades that have their own petiole, sitting on a common axis - rachis.

Compound leaves: A - unpaired pinnate; B - paired pinnate; B - ternary; G - palmately complex; D - doubly paroperistoslozhny; E - twice unpaired pinnate;

Types of dismemberment of the plate:

Classification of simple leaves. Generalized scheme of leaf shapes:

The main types of tops, bases and edges of leaf blades: A - tops: 1 - sharp; 2 - pointed; 3 - dull; 4 - rounded; 5 - truncated; 6 - notched; 7 - pointed; B - bases: 1 - narrow wedge-shaped; 2 - wedge-shaped; 3 - wide wedge; 4 - descending; 5 - truncated; 6 - rounded; 7 - notched; 8 - heart-shaped; B - edge of the sheet: 1 - serrate; 2 - doubly serrate; 3 - gear; 4 - crenate; 5 - notched; 6 - solid.

The main types of venation of the leaves of angiosperms: 1 - pinnate; 2 - pinnatiform; 3 - pinnate; 4 - palmate; 5 - finger-loop-shaped; 6 - parallel; 7 - digitiform; 8 - arcuate.

Methods for attaching leaves to a stem:
Long-petiolate, sessile, vaginal, pierced, short-petiolate, descending.

3) Rosaceae. Forms: trees, shrubs, herbs. Ks - pivotal, many herbaceous have a rhizome. The stem is erect, some are shortened with a mustache, others have spines. Leaf: simple and complex with stipules

Formula: correct, bisexual

Bisexual Ca 5 Co 5 A ∞ G 1-∞ (perianth above ovary).

Inflorescence corymb, raceme, solitary, umbel

Fruit drupe, nut, berry

Subfamilies: spirea (spiraea, fieldfare, volzhanka), rose hips (rose hips, raspberries, blackberries, cotton, strawberries, strawberries), apple (apple, pear, mountain ash, quince, hawthorn), plum (cherry, plum, apricot, peach, bird cherry) , almond)

Meaning: food, lek (pluck), dec (rose, spirea)

Lecture: Cell structure. The relationship of the structure and functions of the parts and organelles of the cell is the basis of its integrity

The cell is a complex multi-component open system, which means that it has a constant connection with external environment through the exchange of energy and matter.

Cell organelles

plasma membrane - This is a double layer of phospholipids, permeated with protein molecules. The outer layer contains glycolipids and glycoproteins. Permeable selectively for liquids. Functions - protective, as well as communication and interaction of cells with each other.

Nucleus. Functionally - stores DNA. Limited by a double porous membrane connected through the EPS with the outer membrane of the cell. Inside the nucleus is nuclear juice and chromosomes are located.

Cytoplasm. It is a gel-like semi-liquid internal contents of the cell. Functionally - provides the connection of organelles with each other, is the environment for their existence.

Nucleus. These are the pieces of ribosomes assembled together. Rounded, very small body located near the nucleus. The function is the synthesis of rRNA.

Mitochondria. double membrane organelle. The inner membrane is assembled into folds called cristae, they contain enzymes involved in oxidative phosphorylation reactions, that is, ATP synthesis, which is the main function.

Ribosomes. Consist of larger and smaller subunits, do not have membranes. Functionally - participate in the assembly of protein molecules.

Endoplasmic reticulum (EPS). Single-membrane structure in the entire volume of the cytoplasm, consisting of cavities of complex geometry. Ribosomes are located on the granular ER, while enzymes for the synthesis of fats are located on the smooth ER.

Golgi apparatus. These are flattened cistern-shaped cavities of the membrane structure. Bubbles with substances necessary for metabolism can be separated from them. Functions - accumulation, transformation, sorting of lipids and proteins, formation of lysosomes.

Cell center. This is the region of the cytoplasm that contains centrioles - microtubules. Their function is the correct distribution of genetic material during mitosis, the formation of the mitotic spindle.

Lysosomes. Single-membrane vesicles with enzymes involved in the digestion of macromolecules. Functionally - dissolve large molecules, destroy old structures in the cell.

Cell wall. It is a dense shell of cellulose, performs a skeletal function in plants.

Plastids. membrane organelles. There are 3 types - chloroplasts, where photosynthesis takes place, chromoplasts, containing dyes, and leucoplasts, which are starch stores.

Vacuoles. Bubbles, which in plant cells can occupy up to 90% of the cell volume and contain nutrients. In animals - digestive vacuoles, complex structure, small size. They are also responsible for the release of unnecessary substances into the external environment.

Microfilaments (microtubules). Protein non-membrane structures responsible for the movement of organelles and cytoplasm inside the cell, the appearance of flagella.

Cell components are interrelated spatially, chemically and physically and are in constant interaction with each other.

A cell is a single living system consisting of two inextricably linked parts - the cytoplasm and the nucleus (color table XII).

Cytoplasm- this is an internal semi-liquid environment in which the nucleus and all organelles of the cell are located. It has a fine-grained structure, penetrated by numerous thin threads. It contains water, dissolved salts and organic matter. The main function of the cytoplasm is to unite and ensure the interaction of the nucleus and all organelles of the cell.

outer membrane surrounds the cell with a thin film consisting of two layers of protein, between which there is a fatty layer. It is permeated with numerous small pores through which ions and molecules are exchanged between the cell and the environment. The membrane thickness is 7.5-10 nm, the pore diameter is 0.8-1 nm. In plants, a fiber sheath forms on top of it. The main functions of the outer membrane are to limit the internal environment of the cell, protect it from damage, regulate the flow of ions and molecules, remove metabolic products and synthesized substances (secrets), connect cells and tissues (due to outgrowths and folds). The outer membrane ensures the penetration of large particles into the cell by phagocytosis (see sections in "Zoology" - "Protozoa", in "Anatomy" - "Blood"). In a similar way, the cell absorbs liquid drops - pinocytosis (from the Greek "pino" - I drink).

Endoplasmic reticulum(EPS) is a complex system of channels and cavities consisting of membranes, penetrating the entire cytoplasm. EPS is of two types - granular (rough) and smooth. On the membranes of the granular network there are many tiny bodies - ribosomes; they do not exist in a smooth network. The main function of EPS is participation in the synthesis, accumulation and transportation of the main organic substances produced by the cell. Protein is synthesized in granular ER, while carbohydrates and fats are synthesized in smooth ER.

Ribosomes- small bodies, 15-20 nm in diameter, consisting of two particles. There are hundreds of thousands of them in every cell. Most ribosomes are located on the membranes of the granular ER, and some are located in the cytoplasm. They are composed of proteins and rRNA. The main function of ribosomes is protein synthesis.

Mitochondria- these are small bodies, 0.2-0.7 microns in size. Their number in a cell reaches several thousand. They often change shape, size and location in the cytoplasm, moving to their most active part. The outer cover of the mitochondria consists of two three-layer membranes. The outer membrane is smooth, the inner one forms numerous outgrowths on which respiratory enzymes are located. The internal cavity of mitochondria is filled with fluid, which houses ribosomes, DNA and RNA. New mitochondria are formed when old ones divide. The main function of mitochondria is the synthesis of ATP. They synthesize a small amount of proteins, DNA and RNA.

plastids unique to plant cells. There are three types of plastids - chloroplasts, chromoplasts and leukoplasts. They are capable of mutual transition into each other. Plastids reproduce by division.

Chloroplasts(60) are green, oval in shape. Their size is 4-6 microns. From the surface, each chloroplast is bounded by two three-layer membranes - outer and inner. Inside it is filled with a liquid, in which there are several dozens of special, interconnected cylindrical structures - gran, as well as ribosomes, DNA and RNA. Each grana consists of several tens of flat membrane sacs superimposed on each other. On the transverse section, it has a rounded shape, its diameter is 1 µm. All the chlorophyll is concentrated in the grains, and the process of photosynthesis takes place in them. The resulting carbohydrates first accumulate in the chloroplast, then enter the cytoplasm, and from it to other parts of the plant.

Chromoplasts determine the red, orange and yellow color of flowers, fruits and autumn leaves. They have the form of polyhedral crystals located in the cytoplasm of the cell.

Leucoplasts colorless. They are found in unpainted parts of plants (stems, tubers, roots), have a round or rod-shaped shape (5-6 microns in size). They store reserves.

Cell Center found in animal and lower plant cells. It consists of two small cylinders - centrioles (about 1 micron in diameter) located perpendicular to each other. Their walls consist of short tubes, the cavity is filled with a semi-liquid substance. Their main role is the formation of the division spindle and the uniform distribution of chromosomes among daughter cells.

Golgi complex was named after the Italian scientist who first discovered it in nerve cells. It has a diverse shape and consists of cavities limited by membranes, tubules extending from them and bubbles located at their ends. The main function is the accumulation and excretion of organic substances synthesized in the endoplasmic reticulum, the formation of lysosomes.

Lysosomes- rounded little bodies with a diameter of about 1 micron. From the surface, the lysosome is limited by a three-layer membrane, inside it there is a complex of enzymes that can break down carbohydrates, fats and proteins. There are several dozen lysosomes in a cell. New lysosomes are formed in the Golgi complex. Their main function is to digest food that has entered the cell by phagocytosis and remove dead organelles.

Organelles of movement- flagella and cilia - are cell outgrowths and have the same structure in animals and plants (their common origin). The movement of multicellular animals is provided by muscle contractions. The main structural unit of a muscle cell is myofibrils - thin threads more than 1 cm long, 1 micron in diameter, arranged in bundles along the muscle fiber.

Cell inclusions- Carbohydrates, fats and proteins - are non-permanent components of the cell. They are periodically synthesized, accumulated in the cytoplasm as reserve substances and used in the course of the life of the organism.

Carbohydrates are concentrated in grains of starch (in plants) and glycogen (in animals). There are many of them in liver cells, potato tubers and other organs. Fats accumulate in the form of droplets in plant seeds, subcutaneous tissue, connective tissue etc. Proteins are deposited in the form of grains in animal eggs, plant seeds and other organs.

Nucleus one of the most important organelles in the cell. It is separated from the cytoplasm by the nuclear membrane, consisting of two three-layer membranes, between which there is a narrow strip of semi-liquid substance. Through the pores of the nuclear envelope, the exchange of substances between the nucleus and the cytoplasm takes place. The cavity of the nucleus is filled with nuclear juice. It contains the nucleolus (one or more), chromosomes, DNA, RNA, proteins and carbohydrates. The nucleolus is a rounded body ranging in size from 1 to 10 microns or more; it synthesizes RNA. Chromosomes are only visible in dividing cells. In the interphase (non-dividing) nucleus, they are present in the form of thin long filaments of chromatin (DNA-to-protein connections). They contain hereditary information. The number and shape of chromosomes in each species of animals and plants are strictly defined. Somatic cells that make up all organs and tissues contain a diploid (double) set of chromosomes (2 n); germ cells (gametes) - haploid (single) set of chromosomes (n). The diploid set of chromosomes in the nucleus of a somatic cell is created from paired (identical), homologous chromosomes. Chromosomes of different pairs (non-homologous) differ from each other in shape, location centromeres and secondary stretches.

prokaryotes- These are organisms with small, primitively arranged cells, without a clearly defined nucleus. These include blue-green algae, bacteria, phages and viruses. Viruses are DNA or RNA molecules covered with a protein coat. They are so small that they can only be seen with an electron microscope. They lack cytoplasm, mitochondria and ribosomes, so they are not able to synthesize the protein and energy necessary for their life. Once in living cell and using other people's organic matter and energy, they develop normally.

eukaryotes- organisms with larger typical cells containing all the main organelles: nucleus, endoplasmic reticulum, mitochondria, ribosomes, Golgi complex, lysosomes and others. Eukaryotes include all other plant and animal organisms. Their cells have a similar type of structure, which convincingly proves the unity of their origin.