Budova microtubules and their functions. Microtubules, their functions

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Microtubules are structures, in which 13 protofilaments, which are composed of heterodimers - i-tubulin, are laid along the stake of an empty cylinder. The outer diameter of the cylinder is close to 25 nm, the inner diameter is close to 15 nm.

One of the ends of the microtubule, the titles of a plus-kind, constantly comes to itself a free tubulin. In the protilazhny kіntsya - minus-kіntsia - tubulin units are split.

Three phases are seen in the illumination of microtubules:

• single phase, or nucleation. The stage of microtubule nucleation, if tubulin molecules begin to fold at the great light. Thus, the transition is more pronounced, the tubulin is lowered to the already assembled microtubule, so the phase is called enhanced;
• polymerization phase, or elongation. As a result, the concentration of the free tubulin of the temple, its polymerization is observed more lower depolymerization on the minus-kintsi, for which the microtubule is subdued. In the world, the increasing concentration of tubulin drops to critical, and the speed of growth increases right up to the entrance to the offensive phase;
• the phase of a stable state. Depolymerization changes polymerization, and the growth of microtubules bulges.

Laboratory studies show that the folding of microtubules with tubulin is less likely to occur in the presence of guanosine triphosphate and magnesium ions.

Dynamic instability

Microtubules with dynamic structures and cells are constantly polymerized and depolymerized. The centrosome, localized near the nucleus, protrudes from the cells of the creature and rich protists as a microtubule organization center (MCMT): the stench grows from it to the periphery of the cell. At the same time, microtubules can quickly pin their growth and shorten back to the centrosome right up to complete collapse, and then again. When arriving at the microtubule, the tubulin molecules, which carry GTP, form a “cap” that ensures the growth of the microtubule. As a local concentration of tubulin falls, due to beta-tubulin GTP is progressively hydrolyzed. As a result, the GTP “caps” on the tip will be hydrolyzed again, in order to cause the microtubule to dry disintegration. In this manner, the folding of that dissection of microtubules is tied with GTP energy vitrates.

Dynamic instability of microtubules plays an important physiological role. For example, when the cells are split, the microtubules grow in an arc and adhere to the correct orientation of the chromosomes and the establishment of the mitotic spindle.

Function

Microtubules in cells are vicarious like "slats" for the transport of particles. Membrane bulbs and mitochondria can move along their surface. Transportation by microtubules creates proteins, called motors. These are high molecular weights that are composed of two important (with a mass of about 300 kDa) and a small number of light lances. In important lancers, one can see the head and tail domains. Two head domains are connected with microtubules and water dviguns, and the tail domains are connected with organelles and other internal organelles that support transport.

There are two types of motor proteins:

• cytoplasmic days;

Days move the vantage only from the plus-point to the minus-point of the microtubules, from the peripheral regions of the clitin to the centrosome. Kinezini, on the other hand, move to the plus-end, that is, to the clitinous periphery.

The movement is charged for the energy of ATP. The main domains of motor proteins for which ATP-zv'yazuvalny business.

For the transport function, microtubules form the central structure of the flagellum - the axoneme. The typical axoneme contains 9 pairs of combined microtubules along the periphery and two identical microtubules in the center. Three microtubules are folded so centrioles and a spindle under, which ensures the separation of chromosomes to the poles of the cells during mitosis and meiosis. Microtubules take part in the subtrial form of clitin and the degeneration of organoids (zocrema, Golgi apparatus) in the cytoplasm of clitin.

Roslinn_ microtubules

Microtubules of roslin are highly dynamic warehouses of the cytoskeleton, they are involved in important clitin processes, zocrema, chromosome segregation, phragmoplast formation, microcompartmentalization, intracellular transport, as well as on maintaining the constant form and polarity of clitin. Mobility of microtubules is ensured by dynamic instability, transfer of polymers by motor proteins, treadmilling (en: Treadmilling) and the hybrid mechanism of treadmilling with dynamic instability, plus-kind and significant depolymerization.

Organization and dynamics

Microtubules are overworldly sensitive to biotic and abiotic factors of the superfluous medium (cold, lightening, dryness, salinity, infusion of herbicides and pesticides, flooding, squeezing, influx of an electric field, pressure and gravity), as well as to phytohormones, antimitotic preparations and other biologically active drugs. Microtubules are empty polar cylindrical filaments with a diameter of over 24 nm, which are taken from α- and β-tubulin heterodimers, and form 13 protofilaments in the head-to-tail position.

The clitins of the greater roslins have microtubules:

Proteins associated with microtubules

All components of the cytoskeleton and other organelles are associated with a number of specific proteins associated with microtubules ( BAM). Creatures have the most famous BAM є tauі BAM2, as they stabilize microtubules and attach them to other cellular structures, as well as transport proteins dynein and kinesin. Functionality of different groups of growing microtubules BAM 65 regulatory kinases and phosphatases. Zocrema, a highly conserved animal homologue of BAM65, is important for the acquisition of singful configurations by microtubules, stretching the growth of growth. Orientation and organization of different populations and types of microtubules and tissue- and organ-specific.

Lateral cylindrical growths of trichoblasts, root hairs, reach a significant longevity of the hairline with a constant diameter in Arabidopsis thaliana L. (immature ~ 6-10 nm; mature - over 1 mm) and are characterized by high-polar cytoarchitecture. Podovzhennya їх vіdbuvaєtsya for the help of the upper ranks (eng. tip growth ) a path of polarized exocytosis, which is indicated by a gushing strum of the cytoplasm, a gradient of cytoplasmic Ca 2+, the activity of F-actin and displacement of the clitinum up to the top of the hair. At the early stages of the development of root hairs of 3-day-old seedlings of Arabidopsis thaliana L., the growth rate is 0.4 µm/min, sooner to 1-2.5 µm/min.

A population of cortical microtubules is organized for growing clitins, which have all the development of root hairs. During the transition from the germinal stage to the lower stage, the cortical microtubules of the tops of the hairs are not visualized, the shards are endoplasmic microtubules. Cortical microtubules are orientated subabove chi spirally. In maize Zea mays L. and lettuce Lactuca sativa L., the initiation of the growth of root hairs is associated with the reorganization of the CMT population in trichoblasts. Population control stability and direct apical growth of root hairs. The difference between several standard parameters in the dynamic instability of the CMT in vivo - the level of growth activity, the flexibility of the selection, the frequency of transitions from the selection to the growth stage ("bow") and navpak ("catastrophe") showed that cortical microtubules (CMT) are similar to the dynamics in young root hairs what did you see. The network of microtubules is reorganized in response to minimal parameters of the navkolyshny medium and stimuli of differentiation in a way of varying indications in dynamic instability.

Notes

Div. also

From the appearance of an electron microscope, it was clear that the cytoplasm of the clitin is organized in a richly folded way, it moved earlier, between organelles, sharpened membrane, and other organelles on the ribosome and centriole cluster, and a clear subdivision. Later, in the distance, a more fine structure was revealed in the matrix of the cytoplasm, which before that seemed to be structureless. Here the folding of the fibrils was revealed. Among them, it is possible to distinguish between three types: microtubules, microfilaments and intermediate filaments. Their functions are related to the clitin's movement or the internal clitin's movement, as well as to the construction of the clitin to improve its shape.

microtubules

Mayzhe, in all eukaryotic cells, there are empty cylindrical non-decomposed organelles, which are called microtubules. These are thin tubes with a diameter of approximately 24 nm; Their walls with a thickness of about 5 nm are formed from spirally packed globular subunits of the protein. tubulin(Fig. 7.24). Rice. 7.21 give information about what microtubules look like on electron micrographs. Dovzhin stink can reach a few micrometers. Sometimes, in the walls, through the sings of the interstices, steps enter, which establish ligaments or jumpers from the suicidal microtubules, as it is possible to posterize in the veins and flagella. Grow microtubules from one cycle in a way to add tubulin subunits. Tse growth is attached to the influx of some chemical speeches, zokrema under the infusion colchicine, which vikoristovuyut schodo funktsіy mikrotrubochok. Growing up, maybe, you can only grow up for the obviousness of the matrix; Let's imagine that the role of such matrices is played by other calculus structures, seen from cells and yak, like z'yasuvalosa, are formed from tubulin subunits. In creatures of the clitin, the same function is obviously played by the centrioles, in the connection with which they are sometimes called the centers of organization of microtubules. Centrioles contain short microtubules (Fig. 22.3).

Microtubules take part in various internal cellular processes; Deyaki mi here zgadaemo.

Centrioles, basal tubules, and flagella. Centrioles - all hollow empty cylinders (less than 0.3-0.5 microns and about 0.2 microns in diameter), which are sharpened in all living clitins and clitins of lower dews; stench rises in pairs in a characteristic area of ​​the cytoplasm, known to be named centrosome or centrosphere. The cutaneous centrole is stimulated by nine triplets of microtubules, as shown in Fig. 22.3. On the cob, under the nucleus of the centrioles, two new pairs of centrioles diverge to the poles of the spindle - the structure, beyond the equator, which is superior in front of the separation of the chromosomes (section 22.2). The spindle itself is folded into microtubules, when folded, they engrave the role of the center in the organization. Microtubules regulate the distribution of chromatids or chromosomes (Ch. 22). In the clitins of the growing roslins, the centrioles are daily, although the spindle in them, when the nucleus is split, is settled. It is possible that in these clitins there are even more distant centers of organization of microtubules, it is impossible to induce with the aid of an electron microscope. Below, when looking at the internal clitin transport, we can see another possible function of the centrioles as a center for the organization of microtubules.

Centrole for the structure is identical basal tiltsya, which were called earlier kinetosomes or blepharoplasts. The basal tilts always appear at the base of the veins and flagella. Obviously, the stench is utvoryuyuyutsya path podvoennya tsentriole, scho beat the basal tіltsyu. Incidentally, the basal tubules also function as the center of microtubule organization, which is why the flagellum is also powerfully characterized by the expansion of microtubules ("9 + 2"; section 17.6 and Fig. 17.31).

At the spindle, as well as at the veins and flagella, the ruhs are formed for the forging of the microtubules; in the first case, the result of this forging is the separation of chromosomes and chromatids, while in the other case, the result of this forging is a breakdown of the chromosomes and chromatids. Reports and processes are described in goal. 17 and 22.

Internal transport. Microtubules also take part in the displaced other clitin organelles, for example, the Golgi bulbs, which help to direct them to the clitin plate, which is formed, as can be seen in Fig. 7.21. In clitins, there is an uninterrupted transport of the Golgi bulbs and, in order, the transport of the bulbs, which pass through the ER and move to the Golgi apparatus. The time-traffic shift allows to reveal the movement that occurs in rich clitins, as well as larger organelles, for example, lysosomes and mitochondria. Such movements can be in order or out of order; vvazhayut that stench is characteristic of all clitin organelles. The movements are reduced, as a result of which the microtubule system has been damaged. The microtubules in clitins are already clearly visible behind the help of the method immunofluorescent microscopy, based on the advent of fluorescent markers to antibody molecules that specifically bind to the protein, has proved to be worthwhile. As soon as antibodies are specific to tubulin, then with a light microscopy it is possible to take a picture similar to that, as shown in Fig. 7.25.

It is important that the microtubules diverge radially from the centrosphere, in the middle of which the centrioles expand. Satellite proteins around the centrioles function as centers of organization of microtubules.

cytoskeleton. The cream of the overhauled functions of the microtubules plays a passive structural role in the clitins: the other tubules, complete the majority of the structures, establish the supporting system of the clitin, a kind of cytoskeleton. The stench is to adopt a specific form of cells in the process of differentiation and substitution of forms of differentiated cells; often the stench rozes in the zone, which directly adjoins to the plasma membrane. In the axons of the nerve cells, for example, there are bundles of microtubules, which later expand (possibly, stinks also take part in the transport of the axon). It has been shown that living cells, in which the system of microtubules is weak, have a spherical shape. In growing cells, the growth of microtubules shows the growth of cellulose fibers, which is observed when the cell wall is stimulated; in this way, microtubules indirectly determine the shape of the cell.

Microfilaments

Microfilaments are called narrow threads of protein with a diameter of 5-7 nm. It has recently been shown that the number of threads present in eukaryotes in the great population are made up of protein actin close to being avenged in m'yazakh. In all vine clitins, actin becomes 10-15% of the total amount of clitin protein. Immunofluorescence microscopy revealed that the actin cytoskeleton is similar to the cytoskeleton of microtubules (Fig. 7.26).

Often, microfilaments are woven into bundles or bundles without a middle under the plasma membrane, as well as on the surface between the rough and unbroken cytoplasm (in growing clitins, cyclosis is suspected). Obviously, microfilaments also take part in endocytosis and exocytosis. In clitiny, threads of myosin (another important meat protein) also appear, although their number is significantly less. Interactions between actin and myosin underlie the rapid development of ulcers (section 17.4). This situation, in order of lesser evidence, shows that the role of microfilaments in clitins is tied to the rukh (either all clitins zagalom, or other structures in the middle of it). It's true, we don't call the rules like that, like the m'yazi. In some cases, only actin filaments function, and in others, actin and myosin together. The rest is typical, for example, for microvilli (section 7.2.11). In clitins, like the rulers of the movement, the selection of that ruination of microfilaments goes without interruption. As the last butt of vikoristannya microfilaments, it can be shown that from the cytotomy of creatures, stinks form a short ring.

Intermediate filaments

To form the third group of structures, as it was intended to be higher, intermediate filaments (8-10 nm in diameter). Cytofilaments also play a role in Rus and take part in the creation of the cytoskeleton.

The cytoskeleton is made up of polymers of protein nature. The leather polymer is made up of ten thousand identical subunits, tied together from the adopted filaments

The cytoskeleton provides the support for the movement of cells and their mechanical support

The cellular cytoskeleton is composed of three types of polymers: actin filaments, intermediate filaments and microtubules

Mustache polymers are dynamic nature; stench steadily build up and spend subunits

Microtubules are polymers of tubulin subunits.

Microtubules may still function together with molecular motors, as they generate susilla, which leads to the movement of vesicles and other complexes on the surface of microtubules.

Vії і flanks are special organelles that are made up of motor proteins, yakі protect ruh clitin in a rare middle or ruh rіdin vzdovzh clitin surface

Chemistries that destroy microtubules, thrive in medicine and the strong state

The photograph is a frame of the video image.
One can see a small tract of cytoplasm of the cells of ssavtsiv.
Evil below you can see the edge of the cell; the core is right-handed eel and is not visible in the frame.
The video shows that the majority of vesicles are being replaced by the post-Soviet Russia.

Cytoplasm eukaryotic clitins are found in the post-Soviet Russia, the shards of the organelle move from place to place all the time. Cey ruh is especially remembered in the cytoplasm of great clitin species of the same form, such as neurons.

roc cytoplasm it is also indicated in other clitins. Rukh organelle necessary vikonannya low functions. Secretory vesicles emerge from the Golgi apparatus, spread out in the middle of the clitinum, and are transported to the plasma membrane, secrete their place in the interstitial medium. At that very hour, the vesicles, internalized into the membrane, are transported to the endosomes. Mitochondria are constantly changing in Russia, and the EPR is constantly expanding and reorganizing.

In mitotic cells chromosomes the humerus vichikovuyutsya in the metaphase plate, and then diverge in the protractile side. Rukh organelles and chromosomes in the right direction and in the right time are provided with a cytoskeleton, which is a protein structure that forms the rail transport system of cells and motor proteins that crash over them.

The cytoskeleton is also important functions: Vіn ensures the fragility of clitin, and also necessary for the organization and structural support of the form of all clitin. Rich clitins collapse either independently, for example, roaming in organisms (creatures of creatures), or moving along with the strum of the superfluous medium (single-clitin organisms and gametes).

Klitini, similar beat the bloody clitins that know and destroy pathogenic bacteria that move on a flat surface. Others, for example, spermatozoa, in order to reach the place of recognition, are transferred to a rare medium. The cytoskeleton provides all the forms of such a circulation of cells and yoga directly. In order of kinematic function, the cytoskeleton provides for the organization of the internal structure of the cell and forms the upper and lower, left and right, as well as the anterior and posterior parts.

Viznachayuchi zagalnu characteristic cytoplasm The cytoskeleton determines the overall shape of the clitinum, straight-cut epithelial clitini, neurons with long thin axons, and dendrites, which in a human can reach one meter in length.

Three video frames of the axon of a living neuron.
The top frame schematically depicts the entire nerve clitina.
Three vesicles, marked with red, yellow and black arrows, were guarded by a stretch of 6 s.
Two vesicles collide directly at the end of the axon, and one directly at the body of the cell.

The cytoskeleton is folded three main types of structural elements: microtubules, microfilaments. There are three types of structures, represented a little lower, with a lot of outrageous powers. Skin protein functions not as an independent molecule, but as a polymer, which is composed of impersonal identical protein subunits. Similarly, like namistini, strung on a thread, utaviruyut namisto, the polymers of the cytoskeleton are vishikovyvayutsya in the cytoplasm, binding together thousands of protein subunits. The main feature of all polymers of the cytoskeleton is that odors are not static structures, but gradually build up and consume subunits. Such a dynamic nature of the polymers of the cytoskeleton allows it to be reorganized, to establish new or accept the functioning of the essential transport pathways to the internal needs.

Want everything three types of structural proteins they show great power, because of them there is uniqueness, which makes it possible to rob it of the most victorious victories of the chants at the church. Therefore, three types of polymers will be looked at perfectly, although stinks often function in tandem.

Tsya come statti on the site are assigned to microtubules. The main subunit that makes up microtubules is tubulin protein. Climbing together, tubulin molecules fill empty tubules with a diameter of about 25 nm. Stars of stench took away their name. One microtubule can contain tens and hundreds of thousands of tubulin molecules and reach a dozen microns.

in such a manner, microtubules buildings expand more and more by half of the increase in the number of eukaryotes. Sound of interphase clitiny to destroy hundreds of long microtubules that pass through the cytoplasm and kill different cells of the clitinum.

Most often they function together with molecular motors, as they are pushed through them. Motor proteins are added to various vantages, including organelles and vesicles, and transport them along the surface microtubules, just like vantages collapse on highways. Microtubules and motor proteins also function together during separation of chromosome replications in mitosis and establish the basis of ruomy structures, like vicarious cells for moving around the homeland or for ensuring the circulation of the homeland and air on the surface. Microtubules and motor proteins are vicoristed by viruses, for example, VIL and adenoviruses, so that the stench could easily reach the nucleus and replicate.

small molecules of organic compounds, as they destroy the polymerization of microtubules, vicorous in medicine and the country's state. Speech, other world building stabilize microtubules, block mitosis and stasis like a cure for cancer. One of these speeches is paclitaxel (Taxol™), the formula of which is presented a little lower and which is victorious for treating ovarian cancer and lactiferous ulcers. Taxol binds to microtubules and stabilizes them, preventing the dissociation of tubulin subunits. Colchicine is also one of the most disgusting, which gives microtubules a proliferative effect, which leads to their dissociation.

The preparation vikoristovuetsya for the treatment of gout, shards microtubule disruption blocking the migration of white blood cells, which are responsible for the ignition process in case of this disease. Low molecular weight speech, which is injected with tubulin, is important for the strong state. For example, Zoxamide™ is a fungicide that specifically binds to fungal tubulins, thereby protecting their growth. The preparation vikoristovuєtsya for the fight against fusarium diseases of potatoes, fungal infections, as well as the mass disease of potatoes in Ireland in 1850. In this hour, there is an active search for new drugs, building contacts with tubulin, and you can know about the congestion in medicine and the strong state.

Dilyanka fibroblast in electron microscopy (levoruch). Numerical filaments are visible.
There are three types of polymers in the right-handed image, from which the cytoskeleton of eukaryotic cells is formed, seen in different colors. Microtubules in fibroblasts. For visualization, the microtubules of the clitinum were trimmed with barvnik, a fluorescent green color.
Microtubules are organized near the central point (marked with a red color) and extend to the cytoplasm.
More microtubules can have enough time to penetrate from one part of the cell into the other side. Budov three small organic molecules that disrupt the process of selection and selection of microtubules.
Paclitaxel (Taxol™) and colchicine are natural products that are found in some types of roslin (Pacific yew and summer autumn).
Zoxamide is a synthetic speech, as it was revealed during the screening of a large number of different low molecular weight cases for the test of impaired functioning of microtubules.

Microtubule proteins

Functions of microtubules

So just like microfibrils, microtubules are shy to the point of functional sluggishness. They are characterized by self-folding and self-assembly, moreover, assortment goes up to tubulin dimers. Vidpovidno microtubules can be represented by a larger or smaller number in the connection with the overflowing processes, or self-assembly, or self-folding microtubules from the fund of globular tubulin of hialoplasma. Intensive processes of self-folding of microtubules are timed to the point of attachment of clitin to the substrate, so that to the point of enhanced polymerization of fibrillar actin from globular actin of hyaloplasma. Such a correlation step in the development of these two mechanochemical systems does not change and reflects their deep functional interrelationships in the full support-speed and transport systems of the cell.

• microtubule formula

• digested with microtubules

• Budova microtube

• micro and macro tubes

• some organelles have microtubules

Main article: Submembrane complex

Rotation of microtubules

Micro-tubules are spread, as a rule, at the largest balls of the membrane-bound cytosol. Therefore, the peripheral microtubules can be seen as a part of the dynamic, organizing microtubule “skeleton” of the cell. However, short-term, and skeletal fibrillar structures of the peripheral cytosol are also connected without intermediary with the fibrillar structures of the main hyaloplasm of the clitin. In functional terms, the peripheral support-velocity fibrillar system of cells is in close interaction with the system of peripheral microtubules. Tse gives us the opportunity to look at the rest as a part of the submembrane system of cells.

Microtubule proteins

The microtubule system is another component of the velocities support apparatus, which is usually in close contact with the microfibrillary component. The walls of microtubules are made up of 13 dimeric protein globules in diameter, the skin globule is composed of α- and β-tubulins (Fig. 6). Remain in large number of microtubules spread in check order. Tubulin becomes 80% of the proteins that are stored in microtubules. Another 20% fall on a portion of high molecular weight proteins MAP1, MAP2 and low molecular weight tau factor. MAP-proteins (microtubule-associated proteins - proteins bound to microtubules) and tau factor are the components necessary for the polymerization of tubulin. In them, the appearance of self-folding microtubules in the way of polymerization of tubulin is very difficult and microtubules, which are established, strongly permeate in native ones.

Microtubules are a rather labile structure, so microtubules of warm-blooded creatures, as a rule, collapse in the cold. Use cold-resistant microtubules, for example, in the neurons of the central nervous system of the vertebrae, their number varies from 40 to 60%. Thermostable and thermolabile microtubules do not depend on the power of the tubule to enter their warehouse; maybe, the values ​​of the vіdmіnnostі are determined by the additive proteins. In native clitins, in pairs with microfibrils, the main part of the microtubular submembrane system is spread in more deeply recumbent sections of the cytoplasm. Material from the site http://wiki-med.com

Functions of microtubules

So just like microfibrils, microtubules are shy to the point of functional sluggishness. They are characterized by self-folding and self-assembly, moreover, assortment goes up to tubulin dimers.

Microtubules, tonka budova, molecular organization

Vidpovidno microtubules can be represented by a larger or smaller number in the connection with the overflowing processes, or self-assembly, or self-folding microtubules from the fund of globular tubulin of hialoplasma. Intensive processes of self-folding of microtubules are timed to the point of attachment of clitin to the substrate, so that to the point of enhanced polymerization of fibrillar actin from globular actin of hyaloplasma. Such a correlation step in the development of these two mechanochemical systems does not change and reflects their deep functional interrelationships in the full support-speed and transport systems of the cell.

Material from the site http://Wiki-Med.com

On this side of the material behind the topics:

• what is the meaning of microtubules

• find out from the text the peculiarities of strelenya microtubules

• functions of microtubules

• abstract about microtubules

• digested with microtubules

In clitins, microtubules take part in a number of thymic (cytoskeleton of interphase clitins, fusiform podil) or post (centrioles, veins, flagellum) structures.

Microtubules are straight long empty cylinders that do not wobble (div.

Microtubules, their functions.

Rice. eighteen). The outer diameter should be close to 24 nm, the inner lumen should be 15 nm wide, and the thickness of the wall should be 5 nm. The wall of microtubules was induced behind a shell of well-placed rounded subunits with a diameter of about 5 nm. In electron microscopy, transverse cuts of microtubules show over 13 subunits, which look like a single-ball ring. Microtubules, seen from different glands (the simplest ones, cells of nerve tissue, spindles below), can create a similar warehouse and remove proteins - tubules. Practically in all eukaryotic clitins in the hialoplasm, it is possible to have two microtubules that do not swell. In great numbers, stinks appear in the cytoplasmic growths of nerve cells, fibroblasts and other cells that change their shape.

One of the functional significance of such microtubules of the cytoplasm is more important in the formation of an elastic, but at the same time stable inner clitin frame (cytoskeleton), which is necessary for the support of the clitin form.

Creating the inner clitin skeleton, microtubules can be factors of the cellular movement oriented as a whole and the inner clitin components, set their own expansion vectors for directing the flows of various speech and for the movement of great structures.

The disruption of microtubules with colchicine disrupts the transport of speech in the axons of nerve clitin, leading to blockade of secretion only then.

9. Lysosomes: life, functions, classification

Lysosomes are a different class of vacuoles with a size of 0.2-0.4 microns, surrounded by a single membrane. A characteristic sign of lysosomes is the presence of hydrolytic enzymes in them - hydrolases (proteinases, nucleases, glucosidases, phosphatases, lipases), which decompose different biopolymers at acidic pH. Lysosome Bulo was declared 1949. de Duve.

Among lysosomes, 3 types can be seen: primary lysosomes, secondary lysosomes (phagolysosomes and autophagosomes) and redundant lysosomes. The difference in the morphology of lysosomes is explained by the fact that these particles take part in the processes of intracellular overetching, facilitating the folding of herbal vacuoles, both exogenous (posoclitinous) and endogenous (intrinsic cellular) movement.

The primary lysosomes, with other membrane bulbs, are about 0.2-0.5 µm in size, filled with a structureless rhechovina to avenge hydrolases, including active acid phosphatase, which is a marker enzyme for lysosomes. The color of the bulbous bulbs is practically more important than the other vesicles on the periphery of the zone to the Golgi apparatus, as well as to avenge acid phosphatase. Miscem її synthesis є granular endoplasmic mesh.

Вторинні лізосоми, або внутрішньоклітинні травні вакуолі, формуються при злитті первинних лізосом з фагоцитарними або піноцитозними вакуолями, утворюючи фаголізосоми, або гетерофагосоми, а також із зміненими органелами самої клітини, що піддаються перетравленню (ау. Речовини, що потрапили до складу вторинної лізосоми, розщеплюються гідролазами to monomers, which are transported through the membrane of lysosomes to hyaloplasmy, destines are recycled, so that they are included before other exchange processes.

However, splitting, overetching of biogenic macromolecules in the middle of lysosomes can go in a number of cells not to the end. And here, in the empty lysosomes, undigested products accumulate. Such a lysosome is called "telolizoma", otherwise it is a redundant body. Zalishkovy tіltsya avenge less hydrolytic enzymes, in some of them there is an improvement in the place, yogo rozbudova. For example, in a person with an old organism in the cells of the brain, liver, and in the meat fibers of telolisosomes, there is an expression of the “pigment of old” - lipofuscin.

The functional significance of autophagocytosis is still unclear. Є pripuschennya, schoy process po'yazaniya іz vydborom iznishchennyam zmenenikh, poshkodzhenikh klinnyh komponentіnі. In this type of lysosomes, the role of internal cellular “purifiers” is played, in order to clean up defective structures.

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CYTOSKELETON

The cytoskeleton is a folding dynamic system of microtubules, microfilaments, intermediate filaments and microtrabeculae. Appointment of components of the cytoskeleton - non-membrane organelles; skin from them I make in a clitiny trivimirna merezh with a characteristic rose subdivision, as well as interchange with merezha with other components. The stench also enters the warehouse to a number of other foldedly organized organelles (viy, jgutikov, microvilli of the clitin center) and clitin spoluk (desmosomes, napіvdesmosom operate desmosomes).

The main functions of the cytoskeleton:

1. substitution and change of the form of the clitin;

2. rozpodіl that relocation of the components of the clitin;

3. transport of speech in the clitin and in it;

4. ensuring cell friability;

5. the fate of interstitial half-lifes.

microtubules- The largest components of the cytoskeleton. The stench is an empty cylindrical seal, which can shape the shape of the tubules, up to a few micrometers long (in flagella more than 50 nm) with a diameter of about 24-25 nm, with a wall thickness of 5 nm and a diameter of lumen of 14-15 nm (Fig. 3-14).

Rice. 3-14. Microtubule removal. 1 - tubulin monomers that make up protofilaments, 2 - microtubule, 3 - microtubule bundle (MT).

The wall of a microtubule is made up of spirally laid threads - protofilaments with a thickness of 5 nm (there are 13 subunits on the transverse cut), made up of dimers from protein molecules of α- and β-tubulin.

Functions of microtubules:

(1) sublimation of the formation of the polarity of the clitinum, subdivision of the її components,

(2) provision of domestic transport,

(3) ensuring the circulation of the viy, chromosomes in the mitosis (to form an achromatin spindle, which is necessary for the clitin hem),

(4) the establishment of the base of other organelles (centrioles, viy).

Rotation of microtubules. Microtubules grow in the cytoplasm at the storage of several systems:

a) at the sight of the next few elements, scattered throughout the cytoplasm and formed lines;

b) in tufts, the stinks are tied with thin transverse layers (in neuronal growths, in the warehouse of the mitotic spindle, spermatids, peripheral platelets);

c) often zlivayuschisya one with one of the formation of pairs, or bletіv (in the axonemі vіy and jgutikov), and triplets (in the basal body and centriole).

Utvorennya that ruynuvannya microtubules. Microtubules є labile system, in yakіy є rivnovaga between їx constant selection and dissociation. Most of the microtubules have one end (which is designated as “-” anchoring, and the other (“+”) is free and takes part in their swelling or depolymerization. satellite - satellite)), which is why it is still called the centers of microtubules organization (MCMT). µm/min., and the fringe is renewed less lower for the first year, before the CMMT also the centers of the chromosomes are added.

Perekonlivі sosledi have shown that after in'єktsії tagged amino acids near the body clitin and amino acids are clayed by bodies and are included to the protein, which then is carried along the axon to the end. In these cases, two main types of axonal transport have been established: general transport, which is close to 1 mm in the haul, and swedish, which goes as far as hundreds of millimeters in the lobe. (Shepperd)

Linkage of microtubules with other structures of the clitinum and interdisciplinary bop is observed at low proteins, violating different functions. (1) Microtubules for additional proteins to attach to other cellular components. (2) For their own length, the tubules make up the numerical scales (as they are formed from proteins associated with microtubules) up to a few tens of nanometers. Zavdyaki to those who are so white successively and reversibly link with organelles, transport bulbs, secretory granules and other secretions, microtubules (as they themselves cannot be short-lived) ensure the transfer of designated structures behind the cytoplasm. (3) Active proteins, associated with microtubules, stabilize their structure, and linking to their free edges, transcend depolymerization.

The suppression of self-selection of microtubules for additional help is low in speech, which is mitosis inhibitors (colchicine, vinblastine, vincristin), which induces the death of clitin, which is shvidko dilyatsya. For this reason, people from such speeches are successfully vicorated for the chemotherapy of puhlins. Blockers of microtubules also disrupt transport processes in the cytoplasm, secretion, and axonal transport in neurons. Ruinuvannya microtubules to produce to change the form of cells and disorganization and structure of the sub-organelles.

Clinical center (cytocenter)

The clitiny center is formed by two empty cylindrical structures with a length of 0.3-0.5 microns and a diameter of 0.15-0.2 microns - centrioles, which are located close to each other at mutually perpendicular planes (Fig. 3-15). The skin centriole is composed of 9 triplets of microtubules, which are often angry (A, B and C), tied with transverse whites with mystka ("handles"). At the central part of the centriole, there are microtubules (for some reason, there is a special central thread here), which is described by the formula (9x3) + 0.

Microfilaments

Skin triplet of centrioles of bandages from spherical bodies with a diameter of 75 nm - satellites; rozbіzhnі vіd them microtubules settle the centrosphere.

Rice. 3-15. The clitin center (1) and the structure of the centriole (2). The clitiny center is made up of a pair of centrioles (C), splayed at mutually perpendicular planes. Skin C is composed of 9 links one by one triplets (TR) microtubules (MT). With skin TR for additional help of lower satellites (C) - globular proteins of the body, which are included in MT.

In clitiny, which is not seen, one pair of centrioles (diplosome) appears, as it sounds like it is rotting near the nucleus. Before splitting in the S-period of interphase, duplication of the centrioles of the pari occurs, and under a direct cut to the skin mature (maternal) centriole, a new (daughter) centriole is formed, an immature procentriole, in the umbilical cord there are only 9 single microtubules, re-create. Pairs of centrioles diverge to the poles of the clitinum, and during the mitosis of the stench they serve as centers for the establishment of microtubules of the achromatin spindle below.

Rice. 3-16. Viya. 1 - late view, 2 - transverse view. BT — basal body (made by triads of microtubules), TSOMT — microtubule organization center, BC — basal root, PL — plasmolema, MTA — microtubule A, MTV — microtubule B, PMT — peripheral microtubules, CMT — central microtubules, CO — central tunic. DR - denine handles, RS - radial spokes, HM - nexin needles.