Cell

Cytology - a science studying a structure, the basic functions and a cell role. Aspects of studying of cytology - cells of multicellular animals, plants, unicells which number bacteria concern, the elementary and unicellular seaweed. And as the cytology studies a structure and a chemical compound of cells, intracellular structures and their functions, functions of cells in an organism of animals and plants, reproduction and development of cells, adaptation of cells to environment conditions.

Today the cytology directly depends on other sciences, as well as they from it.

The cytology has the close connections with biological sciences, for example with botany, zoology, physiology, the doctrine about evolution of the organic world, and also with molecular biology, chemistry, physics, mathematics. Cytology - young enough science, its age of all about 100 years though the term "cell" is known already more than 300 years. In the middle of XVII century Robert Hooke, surveying a thin section of a stopper by means of a microscope has seen, that the stopper consists of small cells - cells. Then it for all history of mankind has applied for the first time the term "cell".

The cellular theory

To the middle of XIX century enough extensive knowledge of a cell, and their basis Theodor Schwann in 1838 have collected has formulated the cellular theory. Having generalised available knowledge of a cell, it has shown, that the cell represents basic unit of a structure of all live organisms, and has declared, that cells of animals and plants are similar on the structure. These positions became the major proofs of unity of a parentage of all live organisms, unities of all organic world. Schwann has brought in a science correct understanding of a cell as independent vital unit, the least unit live - out of a cell a life cannot exist.

Studying of the chemical organisation and cell structure has led to a conclusion what exactly chemical processes underlie her life and support processes occurring in it. That cells of all organisms are similar on a chemical compound, at them the basic processes of a metabolism the same proceed.

Modern cellular - the theory includes following positions:

• The cell - is basic unit of a structure and development of all live organisms;
• Cells of all organisms are similar (are homologous) on the structure, a chemical compound, the basic implications of vital activity and a metabolism both unicellular, and multicellular;
• Reproduction of cells occurs by division of a maternal cell into some identical daughter cells;
• In difficult metaphytes of a cell are grouped on function carried out by them and form tissues. All organs of an organism which are closely bound among themselves and subordinated to humoral and nervous systems of regulation consist of tissues.

Cell researches are of great importance for a solution of diseases.

As in cells arise and the pathological changes leading to occurrence of malignant diseases start to develop. To understand a role of cells in development of diseases, we will result some examples. One of serious diseases of the person - a diabetes.

The reason of its occurrence is insufficient activity of cells of the pancreas developing a hormone insulin which participates in regulation of a sugar exchange of an organism. Malignant changes which lead to development of cancer tumours, also arise in cells.

At studying of a structure and functions of cells various unicellular and metaphytes has shown, that on the structure they are parted on two groups. The first group includes bacteria and blue-green seaweed. These organisms have more simple structure of cells. Them name procaryotes. The second group includes all other organisms: from unicellular green seaweed and the elementary to the higher floral plants, mammal, including person. These kinds of organisms have difficult arranged cells which name nuclear or eukaryotes. These cells have a nucleus and the organoids which are carrying out specific functions.

There is one more group of organisms which does not concern neither to pro-nor eukaryotes. It represents the noncellular form of a life in it the viruses in which studying the virology is engaged enter.

Structure and functions of a cover of a cell

The cell of each of organisms, represents integrated live system which consists of three parts inseparably linked among themselves:

Cell Cover

The cell cover directly co-operates with an environment and with the next cells (in metaphytes). It consists of an external layer and a plasmatic membrane. Cells of animals and plants differ on a structure of their external layer. At plants, and also at bacteria, blue-green seaweed and mushrooms the cell is covered with a dense cover, or a cellular wall. At the majority of plants it consists of a fat. The cellular wall plays exclusively important role: it represents an external skeleton, a protective cover, provides safety of vegetative cells. Though the cellular wall dense enough, but through its wall passes water, salts, molecules of many organic substances. A blanket of cells of animals unlike cellular walls of plants very thin, elastic. He cannot be seen in a light microscope and it consists of various polysaccharides and fibers. The blanket of animal cells has received the name a glycocalix. The glycocalix carries out first of all function of a direct connection of cells of animals with an environment, with all substances surrounding it. Having an insignificant thickness (it is less 1 microns), the external layer of a cell of animals does not carry out a basic role what is inherent to cellular walls of plants. Glycocalix formation as well as cellular walls of plants, occurs thanks to vital activity of cells.

Plasmatic membrane

Under a glycocalix and a cellular wall of plants the plasmatic membrane adjoining immediately with a cytoplasma is located. The thickness of a plasmatic membrane is insignificant, studying of its structure and functions probably only by means of a supermicroscope.

The structure of a plasmatic membrane includes lipoproteins (zhiro-fibers). They are located ordered and bridged with each other by chemical bonds. On modern representations of a molecule of lipids in a plasmatic membrane are located in two ranks and form, so-called, bilipid a layer. Molecules of fibers settle down in a layer of lipids, plunging in it on different depth.

Fiber molecules are located not permanently, that provides dynamism of a plasmatic membrane.

The plasmatic membrane carries out many the important functions from which will catch sight of vital activity of cells: barrier function, a skeleton of a cell which gives it certain structure. One of the main functions is transport of substances through a membrane. So, in a cell arrive ions amino acid hormones (not fibers), carbohydrates, Adepses, and are deduced products of synthesis and products of vital activity of a cell. Transport occurs with the assistance of fibers, because of a gradient of concentration, etc.

The cells forming at multicellular animals various tissues (epithelial, muscular, etc.), are bridged with each other by a plasmatic membrane. In junctions of two cells the membrane of each of them can form cords or excrescences which give to bonds special durability though there are bonds with the help of a cleft (synapses at animals).

Bond of cells of plants is provided by formation of thin channels which are filled by a cytoplasma and are limited by a plasmatic membrane. On such channels which are passing through cellular covers, from one cell in another nutrients, ions, carbohydrates and other bonds arrive.

On a surface of many cells of animals, for example various epithelia, there are very fine thin excrescences of a cytoplasma covered with a plasmatic membrane, - microvillis. The greatest quantity of microvillis is on a surface of cells of an intestine where there is an intensive digestion and a nutrition absorption.

Phagocytosis

Large molecules of organic substances, for example fibers and polysaccharides, a particle of nutrition, a bacterium arrive in a cell by a phagocyte. In a phagocyte immediate participation is accepted by a plasmatic membrane. In that place where the cell surface adjoins to a particle of any dense substance, the membrane caves in, forms an excavation and surrounds a particle which in “membranous packing” plunges in a cell. The digestive vacuole is formed and in it the organic substances which have arrived in a cell are digested.

Cytoplasma

Delimited from an environment a plasmatic membrane, the cytoplasma represents internal semifluid medium of cells. In a cytoplasma of eukaryotic cells the nucleus and various organoids settle down. The nucleus, in norm, settles down in the central part of a cytoplasma. In it various includings - products of cellular activity, a vacuole are concentrated also. As a part of the basic substance of a cytoplasma fibers prevail. In a cytoplasma the basic processes of a metabolism proceed, it unites to a nucleus and all organoids in a single whole, provides their interaction, cell activity as uniform integrated live system.

Cytoplasmic reticulum

All internal zone of a cytoplasma is filled by numerous fine channels and the cavities which walls represent the membranes similar on the structure with a plasmatic membrane. These channels branch, bridged with each other and form the network which has received the name of a cytoplasmic reticulum.

The cytoplasmic reticulum is non-uniform on the structure. Two its types - granulous and smooth are known. On membranes of channels and cavities of a granulous network the set of fine roundish little bodies - ribosomes which give to membranes a rough kind settles down. Membranes of a smooth cytoplasmic reticulum do not carry ribosomes on the surface.

The cytoplasmic reticulum carries out many various functions. The basic function of a granulous cytoplasmic reticulum - participation in synthesis of fiber which is carried out in ribosomes.

On membranes of a smooth cytoplasmic reticulum there is a synthesis of lipids and carbohydrates. All these products of synthesis collect in channels and cavities, and then are transported to various organoids of a cell where are consumed or collect in a cytoplasma as cellular includings. The cytoplasmic reticulum binds among themselves the basic organoids of a cell.

Ribosomes

Ribosomes are found out in cells of all organisms. These are microscopical little bodies of the roundish form in diameter of 15-20 nanometers. Each ribosome consists of two unequal particles in the sizes, small and big.

In one cell many thousand ribosomes contain, they settle down or on membranes of a granulous cytoplasmic reticulum, or freely lay in a cytoplasma. The structure of ribosomes includes fibers and RNA. Function of ribosomes is a synthesis of fiber. Fiber synthesis - difficult process which is carried out not by one ribosome, and the whole group including to several tens of incorporated ribosomes. Such group of ribosomes name a polysoma. The synthesised fibers at first collect in channels and cytoplasmic reticulum cavities, and then are transported to organoids and cell sites where they are consumed. The cytoplasmic reticulum and the ribosomes located on its membranes, represent the uniform apparatus of biosynthesis and transportation of fibers.

Mitochondrions

In a cytoplasma of the majority of cells of animals and plants fine little bodies (0,2-7 microns) - mitochondrions contain.

Mitochondrions are well visible in a light microscope with which help it is possible to survey their form, a locating, to count quantity. The internal structure of mitochondrions is studied by means of a supermicroscope. The mitochondrion cover consists of two membranes - external and internal. The external membrane smooth, it does not form any cords and excrescences. The internal membrane, on the contrary, forms numerous cords which are referred to a mitochondrion cavity. Cords of an internal membrane name cristas (an armour. "Crista" - a crest, an excrescence) Number of cristas unequally in mitochondrions of different cells. Them can be from several tens to several hundreds, and especially it is a lot of cristas in mitochondrions of activly functioning cells, for example muscular.

Mitochondrions name “power stations of"cells"as their basic function - synthesis Adenosine - triphosphate (ATP). This acid is synthesised in mitochondrions of cells of all organisms and represents the universal energy source necessary for realisation of processes of vital activity of a cell and the whole organism.

New mitochondrions are formed by division of mitochondrions already existing in a cell.

Plastids

In a cytoplasma of cells of all plants there are plastids. In cells of animals of a plastid are absent. Distinguish three basic types of plastids: green - chloroplasts; red, orange and yellow - chromoplasts; colourless - leucoplasts.

Chloroplast

These organoids contain in cells of leaves and other green organs of plants, and also at various seaweed. The sizes of chloroplasts 4-6 microns, most often they have the oval form. The higher plants in one cell usually have some tens chloroplasts. Green colour of chloroplasts depends on the maintenance in them of a chlorophyll pigment. A chloroplast - the basic organoid of cells of plants in which there is a photosynthesis, i.e. Formation of organic substances (carbohydrates) from inorganic (СО2 and Н2О) at use of energy of a sunlight.

On a structure chloroplasts are similar to mitochondrions. From a cytoplasma the chloroplast is delimited by two membranes - external and internal. The external membrane smooth, without cords and excrescences, and internal forms many the plaited excrescences referred in a chloroplast. Therefore in a chloroplast the considerable quantity of the membranes forming special structures - grans is concentrated. They are combined like a rouleau.

In membranes a gran chlorophyll molecules therefore here there is a photosynthesis settle down. In chloroplasts ATP is synthesised also. Between internal membranes of a chloroplast DNA, RNA and ribosomes contain. Hence, in chloroplasts as well as in mitochondrions, there is a synthesis of the fiber necessary for activity of these organoids. Chloroplasts breed division.

Chromoplasts are in a cytoplasma of cells of different parts of plants: in colours, foetuses, stalks, leaves. Presence of chromoplasts yellow, orange and red colouring of crowns of colours, foetuses, autumn leaves speaks.

Leucoplasts. Are in a cytoplasma of cells of unpainted parts of plants, for example in stalks, roots, tubers. The form of leucoplasts is various.

Chloroplasts, chromoplasts and leucoplasts are capable a cell to mutual transition. So at maturing of foetuses or change of colouring of leaves in the autumn chloroplasts turn to chromoplasts, and leucoplasts can turn to chloroplasts, for example, at gardening of tubers of a potato.

Golgi apparatus

In many cells of animals, for example in nervous, it has the form of the difficult network located round a nucleus. In cells of plants and the elementary Golgi apparatus is presented by separate little bodies of the crescent or rhabdoid form. The structure of this organoid is similar in cells of vegetative and animal organisms, despite a variety of its form.

Into Golgi apparatus structure enter: the cavities limited to membranes and located groups (till 5-10); the large and fine blisters located on the extremities of cavities. All these elements make a uniform complex.

Golgi apparatus carries out many the important functions. On cytoplasmic reticulum channels to it products of synthetic activity of a cell - fibers, carbohydrates and Adepses are transported. All these substances at first collect, and then in the form of large and fine blisters arrive in a cytoplasma and or are used in the cell in the course of its vital activity, or deduced from it and used in an organism. For example, in cells of a pancreas of mammals digestive enzymes which collect in organoid cavities are synthesised. Then the blisters filled with enzymes are formed. They are deduced from cells in a pancreat duct, whence flow in an intestine cavity. One more important function of this organoid consists that on its membranes there is a synthesis of Adepses and carbohydrates (polysaccharides) which are used in a cell and which are a part of membranes. Thanks to Golgi apparatus activity there is an updating and growth of a plasmatic membrane.

Lysosomes

Represent small roundish little bodies. From the Cytoplasma each lysosome is delimited by a membrane. In a lysosome there are enzymes, proteolytic, Adepses, carbohydrates, nucleic acids.

To the alimentary particle which has arrived in a cytoplasma, lysosomes approach, merge with it, and one digestive vacuole in which there is the alimentary particle surrounded with enzymes of lysosomes is formed. The substances formed as a result of digestion of an alimentary particle, arrive in a cytoplasma and are used by a cell.

Possessing ability to active digestion of alimentary substances, lysosomes participate at a distance parts of cells dying off in the course of vital activity, the whole cells and organs. Formation of new lysosomes occurs in a cell constantly. The enzymes containing in lysosomes, as well as any other fibers are synthesised on cytoplasma ribosomes. Then these enzymes arrive on cytoplasmic reticulum channels to Golgi apparatus in which cavities lysosomes are formed. In such kind of a lysosome arrive in a cytoplasma.

The cellular centre. In cells of animals near to a nucleus there is an organoid which name the cellular centre. The basic part of the cellular centre is made by two small little bodies - the centrioles located in a small site of the condensed cytoplasma. Each centriole has the form of the cylinder in length to 1 micron. Centrioles play the important role at cell division; they participate in formation of a spindle of division.

Cellular includings. Carbohydrates, Adepses concern cellular includings and fibers. All these substances collect in a cytoplasma of a cell in the form of drops and grains of various size and the form. They are periodically synthesised in a cell and used in the course of a metabolism.

Cell nucleus

Cell nucleus. Each cell of unicellular and multicellular animals, and also plants contains a nucleus. The form and the sizes of a nucleus depend on the form and the size of cells. In the majority of cells there is one nucleus, and such cells name uninuclear. There are also cells with two, three, with several tens and even hundreds nucleuss. These are multinuclear cells.

Cell chemical compound. Inorganic substances

Nuclear and molecular structure of a cell. In a microscopical cell some thousand substances which participate in various chemical reactions contain. The chemical processes proceeding in a cell, - one of the basic conditions of her life, development and functioning.

All cells of animal and vegetative organisms, and also microorganisms are similar on a chemical compound that testifies to unity of the organic world.

The maintenance of chemical elements in a cell

Elements Quantity (%)

• Oxygen 65-75
• Calcium 0,04-2,00
• Carboneum 15-16
• Magnesium 0,02-0,03
• Hydrogen 8-10
• Sodium 0,02-0,03
• Nitrogen 1,5-3,0
• Iron 0,01-0,015
• Phosphorus 0,2-1,0
• Zinc 0,0003
• Potassium 0,15-0,4
• Copper 0,0002
• Sulfur 0,15-0,2
• Iodine 0,0001
• Chlorine 0,05-0,1
• Fluorine 0,0001

In the table data about nuclear structure of cells are cited. From 109 elements of periodic system of Mendeleyev in cells their appreciable majority is revealed. The maintenance in a cell of four elements - oxygen, Carboneum, nitrogen and hydrogen is especially great. In the sum they make almost 98 % of all contents of a cell. The following group is made by eight elements which maintenance in a cell is estimated in the tenth and 100-th shares of percent. It is sulphur, phosphorus, chlorine, a potassium, magnesium, sodium, calcium, iron. In the sum they make 1.9 %. All other elements contain in a cell in exclusively small quantities (less than 0,01 %)

Thus, in a cell there are no especial elements, characteristic only for wildlife. It specifies in communication and unity of the live and lifeless nature. At nuclear level of differences between a chemical compound organic and not the organic world is not present. Differences are found out at higher level of the organisation - molecular.

Biology of a tumoral cell

The metaphyte cell can exist in two conditions: normal and transformed, i.e. tumoral. The culture of tumoral cells is more convenient for the research purposes in many cases.

The tumoral cell to many biochemical signs differs from the normal. Its most typical distinctive property is ability to continuous division which does not submit to regulatory signals of an organism. As a result of division two are formed of one cell, also capable to uncontrolled division, i.e. ability to noncontrollable division is descended. The augmentation of the size of a tumour occurs at the expense of reproduction of an initial tumoral cell, instead of transformation of new normal cells into the tumoral. From here follows, that from one tumoral cell in an organism there can be tumoral a knot.

Are available direct that proof, that tumours of the person have a monoclonal parentage (a clone - a quantity of the cells which have occurred from one parent cell as a result of its division).

Besides ability to uncontrolled growth two more properties of tumours define their danger to an organism life: ability to an invasion and an metastasizes.

Invasion

Invasion - the phenomenon of germination of a tumour in normal tissues, breaking their food, functioning that leads to death of them.

Metastasizes

The metastasizes is an ability of a malignant tumour to form tumoral knots in the parts of an organism kept away from a primary tumour. Tumoral cells, unlike normal, are badly clamped among themselves. Coming off the basic knot, single tumoral cells are carried by a blood or lymph current on all organism. In some organs they can be late and start to share, that will lead to formation of the new tumoral knots capable to an invasion, thus, even if a tumour the vital organ and in this case ability of a tumour to an metastasizes does its dangerous to a life is amazed not.

Special interest represents a question, whether there can be a return process, i.e. whether the normal can be formed of a tumoral cell? To give the positive answer, certainly, nobody will dare, but at the same time there are the data testifying to theoretical possibility of a degeneration - normalisation of tumoral cells.

It has been noticed, that at introduction of some substances (oil acid, a dimethylsulfoxide, vitamin A, etc.) in cellular culture of a tumour, a cell to some biochemical signs became similar on normal, however at excision of these substances of a cell again got tumoral lines.

Beatrice Mintz, one of researchers of a cancer, replaced a teratoma cell - tumours of spermaries of the black mouse in a blastula cavity (a stage of development of the fertilised ootid) white mouse. Through the put term little mice who differed from control only that they were motley were born - on a white skin there were black strips. Hence, in an environment of normal cells the tumoral cell has joined in organism developments as a normal cell.

At last, each of us heard about wonderful cases of disappearance of tumours and recover sick of a cancer. The analysis of histories of illnesses of the people who were ill in a stage when the medicine was powerless it to help and any treatment was not spent, shows, that very small share of patients for absolutely not clear reasons recovered. Whether tumoral cells in an organism as a result of changes in functioning of all organism perished, whether they turned to normal cells - it is absolutely not known.

So, the cancer on the one hand genetic disease when in advance set program of cellular division and a cell is fractured passes it in a regimen of unceasing self-reproduction, and on the other hand - immune disease as there is a coordination disturbance in system of supervision of that the cells which have broken the law on strict performance of the program of development, were destroyed.

Cloning

The term "cloning" was included into a wide lexicon when experts Roslin Institute, Midlothian, Scotland have informed also existence Dolly the sheep, born an asexual reproduction method. Employees took cells from a thoracal gland of a six-summer pregnant sheep (in that case these cells can share is better), took from the received culture of a nucleus and introduced them in ootids of other lambs preliminary cleared of own nucleuss. After several hundreds experiences one of similar manipulations has gone right: such by on light has appeared Dolly the sheep which genetic code is peer to a code of a sheep-donor.

Cultivation of cells of plants

The polemic caused by successful cloning of some animals, has for some reason left the successes bound to cloning of plants in a shade. After all already for a long time we deal or is immediate with the plants planted on the basis of cloning, or with the substances received from cultivated vegetative cells and tissues. So, by means of the cultivation of a meristem guaranteeing vurusless plants, sold carnations, chrysanthemums, gerberas and other ornamental plants have been deduced everywhere. Also it is possible to buy and flowers of exotic orchids of the plants, which manufacture of clones already has an industrial basis. Some grades of a strawberry, a raspberry, citrus are deduced with use of technics of cloning. Before deducing of a new grade needed 10-30 years, now, thanks to application of methods of cultivation of tissues this period is reduced about several months. The works bound to manufacture on the basis of cultivation of tissues of plants of medicinal and technical substances which cannot be received by synthesis admit rather perspective.

The basis of cultivation of vegetative cells and tissues is made by the information containing in everyone cell on all properties and possibilities of an organism and ability of a cell to an independent metabolism. For cultivation various organs of plants approach. As a rule, use young leaves and axial runaways of the top verticils, and also stolons, tubers, anthers, ends of roots, alar kidneys and other parts of a plant. Meristematic tissues of apexes of runaways and roots have special value for reception virusless clones. The selected material is sterilised by various substances. Thus it is necessary to observe balance of time that, on the one hand, its duration has provided destruction of microorganisms, with another - would not damage a cell of the most vegetative tissue. Preparation of a material for cultivation comes to the end repeated washing with sterile water then it place in the sterile worker to bank on a nutrient medium and raise necessarily in sterile conditions.

Property of a nutrient medium are defined by objects in view of cultivation of a vegetative material as the end-product depends on the set conditions. The nutrient medium happens liquid or firm. It, as a rule, consists of the big number of synthetic substances with the set concentration though there are mediums in which usual products are applied, with addition of certain substances. As the isolated vegetative cells and tissues mostly are heterotrophic, in it integrally bound Carboneum as which source the glucose or sucrose usually serve should contain. Nitrogen is added in the form of Sodium nitritums used by cells by means of a nitrate reductase. Apply also phosphorus, a potassium, calcium, magnesium, Zinci sulfases. A necessary component are vitamins, in particular groups In (In 1, In 2, In 6), a myo-inositol, a biotin, and also amino acids and organic salts. So, the disadvantage of ions of metals interferes with synthesis of fibers, reduces quantity of RNA and leads to augmentation of the maintenance of free amino acids. Iron matters for nuclear fission and for activity of respiratory enzymes. Manipulating concentration of various substances in nutrient mediums, acidity of the last, temperature, light exposure and humidity in chambers for cultivation, it is possible to receive plants and substances with demanded properties. Depending on used vegetative cells and tissues, ways of cultivation distinguish following basic types of structures: callus, suspended, protoplasts, meristematic, anthers.

Callus structures

For callus structures an initial material is callus - it is a tissue formed at plants on places of wounds and promoting their healing. It consists of more or less homogeneous parenchymatous cells, the beginning which is given wound by a meristem. Elements callus are a little differentiated, however near to its surface the growth caused by activity meristemic of cells is observed. Subsequently in a callus probably formation phloem, xylem and other tissues. External cells callus become pith.

For cultivation on the chosen organ do a cut on which all surface the tissue consisting of unorganized growing cells develops. This formed tissue also is cultivated in the set conditions. Depending on a kind of a plant and an object in view it is preliminary necessary to establish structure of nutrient mediums and concentration of the phytohormones demanded for optimum growth. Calli can look very variously. Callus colouring allows to judge formation of secondary substances. If to contain a callus in full darkness, it belovato-yellow. On light it forms a chlorophyll and becomes green. Red light specifies in anthocyan and beta cyanogen presence. To weaken or eliminate these effects, in a nutrient medium add various substances. Brown cells are formed before dying off, therefore such tissue is necessary for placing on fresh medium. At long cultivation calli can lose the morphogenetic potential. After several changes of nutrient mediums and at addition growth hormones the callus differentiates and regenerates, forms axial runaways, roots and, at last, all plant entirely, capable to reproduction and cultivation in a ground. However mostly calli are used as an initial material for cellular or suspended cultivation.

Culture of anthers

The culture of anthers is used for reception of haploid plants. As a rule, the plant is diploid, i.e. in its cells contains two homologous sets of chromosomes. Only germinal cells are haploid. Unripe anthers in which pollen grains are in a stage previous the first division microdispute on vegetative and generative grains are most convenient for reception of haploid culture. After carrying over of sterile anthers on a nutrient medium pollen cells start to share. The intermediate callus develops or at once the haploid germ which later is differentiated in a haploid plant is formed. Such haploid plants are sterile, but they can pass in diploids after influence of a colchicine or merge of protoplasts. So the prolific homozygous pure lines of plants which are of great importance for selection as in the subsequent generations always there are same set signs are formed. Thanks to this method new grades grain and tobacco are deduced, and also numerous herbs with the improved properties are received.

Culture of protoplasts

Cultures of protoplasts receive mainly from the suspension prepared from a mesophil, processing its enzymes blasting cellular walls. As a result of it there can be a joining of another's organellas, and also another's DNA which is built in a genetic material of a nucleus. As surfaces of protoplasts have a negative charge, it is necessary to neutralise their pushing away from each other then they are bridged. After merge there is a neogenesis of a cellular wall. It is formed less than for days then cells start to share. In many cases merges of protoplasts of different parent plants and the subsequent neogenesis through culture of a callus of a new plant with the set properties went right. Merge of protoplasts have grown up, for example, a potato and tomato hybrid.

Suspension culture

For suspension cultures an initial material can be as the isolated whole cells of the chosen organ of a plant, and the crushed callus. The formed cells place on liquid medium and cultivate at constant hashing. Growth of suspended culture occurs in many cases essentially faster, than callus cultures as clumps of cells absorb nutrients considerably a larger general surface, and at a callus it occurs only in that its part which lays on substrate. Thus there is a cell fission. By means of special receptions the suspended culture can be transferred on a firm nutrient medium. Here the capable callus can be formed of cells or complexes of cells by a life. In suspension can arise as well germs which after their carrying over form a new plant.

Meristemic culture

For meristemic cultures use a meristem - cambial the tissue of plants longly keeping ability to division and formation of new cells and differing high metabolic activity. For cultivation isolate cones of increase of runaways, roots, and also alar kidneys. Meristematichesky cultures are more known in gardening as they give the chance to receive virusless clones. From this it is possible to draw a conclusion, that distribution of viruses in various parts of a plant irregular, and the meristem is deprived them. From virusless meristems in a considerable quantity can regenerate genetically identical virusless plants. This way use for deducing of grades of a potato, grapes, and also ornamental plants and in forestry.

Regeneration

Regeneration- the phenomenon of restoration of the whole organism from its part. At cultivation neogenesis can occur different ways: direct neogenesis from cultures of a meristem, apical runaways, alar kidneys and knots, and indirect, with an intermediate stage of a callus. In the latter case are possible also two ways are possible: at органогенезе certain concentration and parities of phytohormones cause formation of adnexal runaways and roots; at a somatic embryogenesis in a callus germs from which the plant grows, then transferred to a ground are formed.