"The woman is created for a man, not a man for a woman" - such a postulate ...
Smooth endoplasmic network.
The endoplasmic network is divided into two types - smooth and rough.
Smooth EPS also calledagranular.
The smooth endoplasmic network occurs and develops at the expense of the granular endoplasmic network (when it is released from ribosomes).
The smooth network consists of tubes whose walls are membranes, channels and bubbles of a smaller cross section than in a rough network.The diameter of vacuoles and tubules smooth endoplasmic network is usually about 50-100 nm. Its functions are as diverse: lipids of membranes are synthesized here, but, besides them, and non-emblems Lipids (for example, special animal hormones), poisonous substances are neutralized by special enzyme complexes, ions accumulate. So, in the transverse muscles, the smooth network serves as a tank of calcium ions. The membranes of this network contain powerful calcium "pumps", which in hundredths of the seconds are transferred to any side a large number of calcium ions. Also synthesized carbohydrates. In specialized cells, the type of smooth network is varied, which is associated with its specific functions in intracellular metabolism.
The smooth network is characterized by the presence of enzyme systems involved in the key
out of the links of metabolism. The smooth endoplasmic network is easily damaged during hypoxia, activation of endogenous phospholipas. Loss of its functions in the cells of rerCK reduces the body's stability to exo and endogenous pathogenic products and contributes to the development of the disease.
The smooth EPS is well developed in those cells in which the synthesis and lipid cleavage processes are coming. These are cells of adrenal glands and seeds (steroid hormones), liver cells, muscular cells, intestinal epithelial cells are synthesized.
In the membranes, the smooth eps is built into hydroxylation enzymes - a special method of oxidation, which is sometimes called microsomal, is used in the synthesis of many lipids (for example: steroid hormones) and for neutralizing various harmful substances.
Electronic micrograph
1 - vacuoles and tubes smooth EPS. There are no ribosomes on their surface facing hyaloplasm. but
here are associated enzyme systems of synthesis and modifies
lipid kation.
Other structures:
2 - mitochondria.
3 - peroxisoma,
4 - Ribosomes.
5 - residual body.
Cell structure. Endoplasmic reticulum
1. Why is the Golgie complex well developed in the cells of the internal secretion gland?
2. In which cells most organides are missing?
3. What is cellular inclusions?
Endoplasmic network (EPS).
The endoplasmic network, or endoplasmic reticulum, is a system of tubes and cavities that permeate cytoplasm Cells. The EPS is formed by a membrane, which has the same structure as the plasma membrane. The tubes and the EPS cavities may occupy up to 50% of the volume of the cell and are not broken anywhere and do not open into the cytoplasm (Fig. 31). There are smooth and rough (granular) EPS. On rough EPS, there are many ribosomes. It is here that most proteins are synthesized. On the surface of the smooth EPS there is a synthesis of carbohydrates and lipids. Substances synthesized on EPS membranes are transferred inside the reticulum tubes and are transported to places of accumulation or use in biochemical reactions. Rough net It is better developed in those cells that synthesize proteins for the needs of the whole organism (for example, protein hormones), and smooth - in those cells that synthesize, for example, sugar and lipids. In the smooth EPS, the calcium ions accumulate - important regulators of all the functions of cells and the whole body.
The complex (apparatus) of Golgi.
The system of intracellular tanks in which substances are accumulated synthesized by the cell is called the (apparatus) of the Golgi. Here, these substances undergo further biochemical transformations are packaged into membrane bubbles and are transferred to those places of cytoplasm, where they are necessary, or transported to the cell membrane and go beyond (Fig. 32). The Golgi complex is built from membranes and is located next to the EPS, but not reported with its channels. Therefore, all substances synthesized on EPS membranes are transferred to the Golges complex inside the membrane bubbles, which are bubble from the EPS and merging then with the Golgji complex. Another important feature of the Golgie complex is a cell membrane assembly. Substances from which the membranes (proteins, lipids) are consisted in the Golgjie complex from the EPS, in the cavities of the Golgi complex, the membranes are collected from which special membrane bubbles are manufactured. They are moving around the cytoplasm in those sites of the cell where it is required to complete membrane.
Kamensky A. A., Kriksunov E. V., Book V. Biology Grade 10
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This is a system of channels and cavities, the walls of which consist of one layer of the membrane. The structure of the membrane is similar to PlasmaMalem (liquid-mosaic), however, the lipids and proteins are somewhat different in a chemical organization. There are two types of EPS: rough (granular) and smooth (agranular).
EPS has several functions.
- Transport.
- Membron-forming.
- Synthesizes protein, fats, carbohydrates and steroid hormones.
- Decreases toxic substances.
- Deposit calcium.
On the outer surface of the membrane, rough EPS, protein synthesis occurs.
2. The smooth EPS membrane contains enzymes that synthesize fats, carbohydrates and steroid hormones.
3. On the smooth EPS membrane, enzymes are located, which neutralize the toxic alien substances that have been in a cage.
Roughly contains on the outside of the membrane matrix a large number of ribosomes that participate in protein synthesis. The protein synthesized on the ribosome through a special channel enters the EPS cavity (Fig. 7) and from there it is distributed to various parts of the cytoplasm (mainly he gets into the Golgji complex). This is characteristic of proteins going on export. For example, for digestive enzymes synthesized in pancreatic cells.
Ribosome IRNK.
Fig. 7. Endoplasmic network:
A - fragments of smooth EPS; B - fragments of rough EPS. B - functioning ribosome on rough EPS.
The smooth EPS membrane has a set of enzymes, synthesizing fats and simple carbohydrates, as well as steroid hormones necessary for the body. It should be noted that in the membrane, the smooth EPS of the liver cells there is a system of enzymes carrying out the splitting of alien substances (xenobiotics) in the cell, including drug compounds. The system consists of a variety of enzyme proteins (oxidizing agents, reducing agents, acetylastors, etc.).
Xenobiotic or medicinal substance (LW), interacting consistently with certain enzymes, changes its chemical structure. As a result, the final product may preserve its specific activity, can become inactive or, on the contrary, to acquire a new property - to become a toxic for the body. The system of enzymes located in the EPS and the chemical conversion of xenobiotics (or LV) is called biotransformation system. Currently, this system is attached great importance, because The specific activity of LV (bactericidality, etc.) in it depends on the intensity of its work and the quantitative content of these or other enzymes.
Studying the content in the blood of an anti-tuberculous substance of Isoniazid, the researchers have encountered an unexpected phenomenon. When admitting the same dose of the drug, its concentration in the blood plasma in different individuals turned out to be unequal. It turned out that people with an intense process of biotransformation isoniazid quickly acetylated, turning into another compound. Therefore, its blood content becomes significantly less than that of individuals with low acetylation intensity. It is logical to conclude that patients with rapid acetylation, for effective treatment, must be prescribed higher doses of the drug. However, another danger occurs, with an isoniazide acetylation, a toxic compound for the liver is formed. Therefore, an increase in the dose of isoniazide in rapid acetylasts may result in lesion of the liver. These paradoxes are constantly found on the path of pharmacology when studying the mechanism of action of drugs and biotransformation systems. Therefore, one of the important issues to solve the pharmacologist is to recommend to introduce such an LV to the practice that would not be rapidly inactivating in the biotransformation system and, moreover, it would not be transformed into a toxic connection to the body. It is known that from the Pharmaceutical Committee recommended by the Pharmaceutical Committee, almost everyone is subjected to biotransformation processes. However, none of them completely lose its specific activity and does not cause significant harm to the body. Such substances such as atropine, leftomycetin, prednisone, norepinephrine and many others fully retain their properties, but passing through the biotransformation system, becomes more soluble in water. So they will quickly be removed from the body. There are substances that activate the biotransformation system, for example, phenobarbital. Thus, in the experiments carried out on mice, they found out that when a large number of this substance invested in the blood flow of a large amount of this substance in the liver cells, the surface of a smooth EPS is doubled over several days. Stimulation of the biotransformation system is used to neutralize toxic compounds in the body. Thus, phenobarbital is used in the treatment of hemolytic disease of the newborn, when the stimulation of biotransformation systems helps the body cope with excess of harmful substances, for example, bilirubin. By the way, after removing a harmful substance, the excess membranes of smooth EPS is destroyed with lysosomes, and after 5 days the network acquires a normal volume.
The substances synthesized in the EPS membranes are delivered to various organides or to the places where they are needed (Fig. 8). The transport role of the EPS is not limited to this, in some parts of the membrane, a protrusion is capable of forming, which are rejected and separated from the membrane, forming a bubble in which all ingredients of the network tubular are contained. This bubble is capable of moving and emptying its contents in a wide variety of cells of the cell, in particular to merge with the Golgji complex.
Rough EPS 
Elements of cytoskeleton
Ribosome
Mitochondria
Core Cage
Fig. 8. A schematic representation of the inside of the cell (the scale is not complied).
It is necessary to note the important role of EPS in the construction of all intracellular membranes. Here begins the very first stage of such construction.
Eps plays a significant role in the exchange of calcium ions. This ion is of great importance in the regulation of cellular metabolism, changing the permeability of the membrane channels, activating various compounds in the cytoplasm, etc. Smooth EPS is the depot of calcium ions. If necessary, calcium is released and takes part in the vital cell of the cell. This feature is most characteristic of the EPS of the muscles. The release of calcium ions from EPS is a link in the complex muscle contraction process.
It is necessary to note the close connection of EPS with mitochondria - cell energy stations. In case of diseases associated with ENERGODIFECT, ribosomes are disconnected from the membrane of a rough EPS. The consequences are not difficult to predict - the synthesis of proteins for export is disturbed. And since such proteins include digestive enzymes, with diseases associated with the ENERGODFECITY, the work of digestive glands will be broken and, as a result, one of the main functions of the body will suffer - digestive. Based on this, the pharmacological tactics of the doctor should be developed.
Golgi complex
In the glands of internal secretion, for example, in the pancreas, some bubbles, separating from the EPS, are flattened, merge with other bubbles, superimposed on each other, like pancakes in a stack, forming a Golgi complex (kg). It consists of several structural elements - tanks, bubbles and tubes (Fig. 9). All these elements are formed by a single-layer membrane of liquid-mosaic type. In tanks, the "maturation" of the contents of bubbles occurs. The latter are reclined from the complex and move in cytosol on microtubule, fibrils and filaments. However, the main path of bubbles is the movement to the plasma membrane. Merging with it, bubbles empty their contents with digestive enzymes in the intercellular space (Fig. 10). From it, enzymes fall into the duct and pour into the intestines. The process of removal with the help of bubbles, the secret is called exocytosis.
1
Fig. 9. Scroll of the Golgi complex: 1 - core; 2 - Yazryshko; 3 - bubbles formed in kg; 4 - tanks kg; 5 - tube.
Membrane
Fig. 10. Formation of tanks kg (g) from bubbles:
1 - core; 2 - Yazryshko; 3 - bubbles formed in CT; 4 - tanks kg; 5 - tube.
It should be noted that exocytosis in the cell is often combined with another important cellular process - construction or updating of the plasma membrane. Its essence is that a bubble consisting of a single-layer liquid-mosaic membrane, approaching the membrane, breaks, breaking at the same time and membrane. After the contents of the contents of the bubble of its edges merge with the edges of the barracks in the membrane, and the gap is "delayed". Another way is characteristic of bubbles, of which lysosomes are further formed. These bubbles, moving along the guide filaments, are distributed throughout the cytoplasm of the cell.
Practically in kg there is a redistribution of proteins synthesized on ribosomes of rough EPS and delivered through EPS channels to kg, some of them goes from kg to export, part remains for the needs of the cell (for example, concentrated in lysosomes). The process of accurate distribution of proteins has a complex mechanism, and during its failures, not only digestive functions can be affected, but all the functions associated with lysosomes. Some authors were very accurately noticed that kg in the cage is a "central railway station", where the redistribution of the flow of passenger proteins occurs.
Some microtubules blindly end.
The kg is a modification of products coming from EPS:
1. Accumulation of incoming products.
2. Dehydration them.
3. Required chemical restructuring (maturation).
Earlier, we noted that the kg is the formation of digestive secrets and lysosomes. In addition to these functions, polysaccharides and one of the main participants in immune responses in the body are synthesized in the organide - Immunoglobulins.
And finally, kg takes an active part in the construction and updating of plasma membranes. Pouring through a plasmaemma, bubbles are able to integrate their membrane into it. For the construction of membranes, substances are used (Fig. 11), synthesized in EPS and the "ripe" on the membranes of tanks kg.
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Exocytosis and education
Membranes cells out
Bubble membranes.
Core cells
Golgi complex
Fig. 11 The scheme for the formation of the plasma membrane fragment from the membrane bubble kg (the scale is not observed).
Function kg:
· Transport (formed bubbles transport enzymes outside or for their own use),
· Forms lysosomes,
· An immunoglobulins, complex sugars, mucoproteides, etc.), forming (kg kg.
· Construction: a) the membrane of bubbles kg can be integrated into the plasma membrane; b) the construction of the cell membranes are connections synthesized in the tank membrane,
· Separating (divides the cell on the compartments).
Lysosomes
Lizosomes have the form of small rounded bubbles, are found in all parts of the cytoplasm, from which a single-layer membrane of liquid-mosaic type is separated. The internal content is uniform and consists of a large number of a wide variety of substances. The most significant of them - the enzymes (about 40 - 60) are cleaving almost all natural polymeric organic compounds that have fallen inside the lysosomes. Inside the lysosom pH 4.5 - 5.0. With such values, enzymes are in active condition. If the pH is close to neutral characteristic of cytoplasm, these enzymes have low activity. This is one of the mechanisms for protecting cells from self-extinguishing in the event that enzymes fall into the cytoplasm, for example, when leased break. On the outside of the membrane there is a large number of a wide variety of receptors that contribute to the combination of lysosomes with endocytosis bubbles. It should be noted the important property of lysosomes - targeted movement towards the object of action. When phagocytosis occurs, the lysosomes move towards the FAGOS. Their movement is noted to destroyed organoids (for example, mitochondria). As we wrote earlier, the directional movement of lysosomes is carried out using microtubules. The destruction of microtubule leads to the termination of the formation of phaglicosa. Phagocyte practically loses the ability to digest pathogenic microorganisms in the blood (phagocytosis). This leads to a severe course of infectious diseases.
Under certain conditions, the lesos membrane is capable of passing inside high molecular weight organic matter hyaloplasm (for example, proteins, lipids, polysaccharides) (Fig. 12. (4,4A), where they are split to elementary organic compounds (amino acids, monosahara, fatty acids, glycerin). These compounds then come out of the lysosomes and go to the needs of the cell. In some cases, the lysosomes can "capture", and then "digest" the fragments of organoids (Fig. 12. (3,3A)) and damaged or outdated cell components (membranes, inclusion) . When fasting, the vital activity of the cells is maintained due to digestion in the lysosomes of a part of the cytoplasmic structures and the use of finite products. Such endogenous food Characteristic for many multicellular.
Endocytosis bubbles formed in the process of endocytosis (phagocytosis and pinocytosis) (Fig. 12. (1,1A) and phagems (Fig. 12. (2,2A)) - also merge with lysosome, forming a phagelicosome. Their internal contents - microorganisms, organic substances, etc. are split by enzymes lysosome to elementary
Microorganisms
Dissolved
Organic 2 3
Substances
Squirrels, Fat Lizosome Fragments
carbohydrate mitochondria
Fig. 12. Lizosomes:
1, 1a - disposal of organic matter hyaloplasm; 2, 2a - disposal of the contents of pinocytous bubbles; 3, 3a - disposal of the contents of phagocytosis bubbles; 4, 4A - enzymatic splitting of damaged mitochondria. 3A - FAGOSOMS.
organic compounds, which, after reaching the cytoplasm, become participants in cellular metabolism. Digestion of biogenic macromolecules inside Lizosoma can go in a number of cells not to the end. In this case, inseparable products accumulate in the cavity of the lysosomes. Such a lysosome is called a residual body. Pigment substances are laid there. In a person, with the aging of the body in the residual calves of brain cells, liver and in muscle fibers, the "anti-aging" - lipofuscin accumulates.
If the above can be conditionally characterized as an action of lysosom at the cell level, the other side of these organoids is manifested at the level of the whole body, its systems and organs. First of all, it concerns the removal of organs dieting during the embryogenesis (for example, the tail in the tip), with differentiation of cells of some tissues (replacement of cartilage by bone), etc.
Given the great importance of the enzymes of lysosomes in the vital activity of the cell, it can be assumed that any violations of their work can lead to severe consequences. In case of damage to the gene controlling the synthesis of any enzyme lysosomes, the latter will have a violation of the structure. This will lead to the fact that "undigested" products will accumulate in lysosomes. If it becomes too much in the cell, the cell is damaged and as a result, the work of the relevant authorities is violated. Hereditary diseases developing in such a scenario are called "Lizosomal accumulation diseases".
It should also be paid to the participation of lysosomes in the formation of the body's immune status (Fig. 13). Finding into the body, the antigen (for example, a microorganism toxin) mainly (about 90%) is destroyed, which protects cells from its damaging action. The remaining antigen molecules are absorbed by the (pinocytosis or phagocytosis) by macrophages or special cells with a developed lysosomal SIS
Bacterium
 |
Antigen
Macrofag
pinositoza
Pinocytosny
Lizosoma
Peptide antigen fragments
Fig. 13. Formation in the macrophage of peptide fragments of antigen
(Scale is not complied).
theme. Pinocytous bubble or phagosome with an antigen is connected to the lysosome and the latter enzymes, cleave the antigen on fragments that have greater antigenic activity and less toxicity than the initial microbial antigen. These fragments in large quantities are taken to the surface of the cells, and there is a powerful activation of the body's immune systems. It is clear that the strengthening of antigenic properties (against the absence of a toxic effect), as a result of lysosomal treatment, significantly speeds up the process of the development of protective immune reactions to this microorganism. The process of cleavage of lysosomes of antigen on peptide fragments is called antigen processing. It should be noted that direct participation in this phenomenon is taken by EPS and the Golgi complex.
And finally, the issue of the relationship between lysosomes and microorganisms, phagocyted cells has been widely considered widely. As we set out earlier, the fusion of the Fagosomes and Lizosomes leads to the digestion of microorganisms in the phagelicosome. This is the most favorable outcome. However, other relationship options are also possible. Thus, some pathogenic (pathogenic) microorganisms during penetration into the cell inside the phagemsomas are distinguished by substances that block the fusion of lysosomes with the phageosome. This makes it possible to preserve them in the Fagios. However, the lifespan of cells (phagocytes) with absorbed microorganisms is small, they disintegrate, throwing into the blood of the phangosomes with microbes. Microorganisms released into the bloodstream can again provoke a relapse (refund) of the disease. Another option is possible when parts of the destroyed phagocyte, including the phagems with microbes, are again absorbed by other phagocytes, while remaining in a living condition and in the new cell. The cycle may repeat quite a long time. The case of a disease with a rapid typhoid in an elderly patient who was still a junior red-Armenian to suffer a rapid tit, fighting in the first equestrian army. After fifty years, not only the symptoms of the disease were repeatedly repeated - even delusional visions returned the old man in the era of the Civil War. The thing is that the rapid typhoid pathogens have the ability to block the process of compounds by Fagos and Lizosom.
Lysosome function:
· Digestive (digesting parts of cytoplasm and microorganisms, supplies elementary organic compounds for cell needs),
· Recycling (cleans the cytoplasm from broken parts),
· Participate in the removal of dying cells and organs,
· Protective (digestion of microorganisms, participation in the immune reactions of the organism).
Ribosomes.
This is a protein synthesis device in a cell. The ribosoma includes two subunits - big and small. Subunits have a complex configuration (see Fig. 14) and consist of proteins and ribosomal RNA (RRNA). Ribosomal RNA serves as a peculiar framework, which is attached to the protein molecules.
The formation of ribosomes occurs in the nucleus of the coder of the cell (this process will be considered below). The formed large and small subunits extend through nuclear pores in the cytoplasm.
In the cytoplasm of ribosomes are in a dissociated or dispersed state, this dissociated ribosomes. In such a state, they are not able to attach to the membrane. This is not a working condition of the ribosome. In the working condition of the ribosome is a organoid consisting of two bonded subunits, between which the IRNN thread passes. Such ribosomes can freely "swim" in cytosole, they are called free ribosomes, or attached to various membranes,
A B C D
Fig. 14. Natural shape of a small (a) and large (b) ribosome subunits. A whole ribosome (B). Conceptual image of ribosomes (g)
for example, the EPS membrane. On the ribosome membrane, it is most often located alone, but an ensemble. The ensemble can be a different number of ribosomes, but all of them are connected by one IRNA thread. It makes the work of Ribosa very effective. While the next ribosome finishes the synthesis of protein and comes with IRNA, other synthesis continue, being in various places of the RNA molecule. Ensemble of such ribosomes on 
turns out polish(Fig. 15).
End of protein synthesis. Start of protein synthesis.
Fig. 15. Scheme of protein synthesis polis.
The drawing of the polysoma consists of five different ribosomes.
Usually, proteins for export proteins are synthesized on membranes, and in hyaloplasm - for cell needs. If the disease is disconnected by the ribosoma from the membrane and the transition to hyaloplasma, then this can be considered as a protective reaction - on the one hand, the cells reduce protein exports and increases protein synthesis into internal needs. On the other hand, such a disconnection of the Ribosoma testifies to the occurrence of the cellular energy unit, since the attachment and retention of ribosomes on membranes requires energy costs, the main supplier of which in the cell is ATP. The lack of ATP naturally leads not only to disconnect the ribosome from the membrane, but also the inability of free ribosa to attach to the membrane. This leads to a shutdown of an efficient protein generator cell from the molecular economy - rough EPS. It is believed that energy deficiency is a serious violation of cellular metabolism, most often associated with violation of energy-dependent processes (for example, in mitochondria).
In the ribosome there are three different sections with which RNA is associated is one for matrix, or information RNA (mRNA, or IRNA), and two for transport RNA. The first is located at the point of contact of the big and small subunit. Of the last two - one plot holds the TRNA molecule and forms connections between amino acids (peptide connections), therefore it is called the R-Center. It is located in a small subunit. And the second serves to hold only the arrived molecule of TRNA loaded by amino acid. It is called a center.
It should be emphasized that during the synthesis of protein, some antibiotics can block this process (we will stop more detailed when we describe the broadcast).
Mitochondria.
They are called "Cell Energy Stations". In eukaryotes in the process of glycolysis, the Krebs cycle and other biochemical reactions formed a large number of electrons and protons. Some of them are involved in a variety of biochemical reactions, the other part is accumulated in special compounds. There are several of them. The most important of them are NAPC and NAPFN (nicotinyndaenindinucleotide nicotinyndenindinucleotide and namentamidenindinucleotide phosphate). These compounds in the form of OPD and NADF are acceptors - original "traps" of electrons and protons. After connecting electrons and protons to them and protons, they turn into NADB and PRFN and are already donors of elementary particles. "Capturing" them in a wide variety of cells, they transfer particles to various cytoplasm departments and, giving them to the needs of biochemical reactions, ensure uninterrupted flow of metabolism. The same compounds supply electrons and protons in mitochondria from cytoplasm and from mitochondrial matrix, where there is a powerful elementary particle generator - the Krebs cycle. NADP and NAPFN, embedded in the electron transfer circuit (see below), passes particles to synthesis ATP. From ATP, the energy is drawn into all the processes going in a cell with considerable energy.
Mitochondria have two liquid-mosaic membranes. Between them is the intermogram space. The inner membrane has folds - cristes (Fig. 16). The inner surface of the Crysta is littered with mushroom-shaped vents having a leg and head.
In mushroom-shaped tales, the synthesis of ATPs occurs. In the thickness of the inner membrane, mitochondria is located enzyme complexes that carry electrons with NADH 2 per oxygen. These complexes are called respiratory chain or chain
Ribosome
A B S.
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|||||||||
Ring DNA
Fig. 16. Mitochondria:
A is the general scheme of the organization of mitochondria. B - Plot Crysts with mushroom-shaped bodies:
1 - outer membrane mitochondria; 2 - intermogram matrix; 3 - internal membrane; 4 - matrix; 5 - Crysta; 6 - Mushroom Tales.
electron nose.Due to the movement e.synthesis of ATP occurs on this complex. ATP is the main energy supplier for all cell processes. Mitochondria are the main consumers of oxygen in the body. Therefore, first of all, mitochondria react to the lack of oxygen. This reaction is unambiguous-alheading oxygen (hypoxia) leads to swelling mitochondria, in the future the cells are damaged and dying.
The various types of eukaryotic cells differ from each other in both the number and form of mitochondria and by the number of Crysta. The content of organelle in the cell ranges within 500 - 2000, depending on the need for energy. So actively working cells of intestinal epithelium contain many mitochondria, and in spermatozoa, they form a network, a worst flavor, providing its energy to move. In tissues with a high level of oxidative processes, for example, in the heart muscle, the number of Crysta many times more than in conventional cells. In the mitochondria of the heart muscle, the number is 3 times more of them than in the mitochondria of the liver.
Mitochondria life is measured by days (5 - 20 days in different cells). Outdated mitochondria is dying, disintegrated into fragments and disposed of lysosomes. In exchange, new, which appear as a result of dividing the existing mitochondria.
Usually, 2 - 10 DNA molecules are located in the mitochondrial matrix. These are ring structures encoding mitochondral proteins. In mitochondria, there is a whole protein synthesis device (ribosome, IRNA, TRNA, amino acids, transcription enzymes and broadcasts). Therefore, in mitochondria, the processes of replication, transcription and broadcast are carried out, ripening of IRNA - processing. Based on this, mitochondria are semi-autonomous units.
The essential moment in the activity of mitochondria is the synthesis of steroid hormones and some amino acids (glutamic). Outdated mitochondria can perform a deposit function - accumulate products of excretion or accumulate harmful substances that have been in a cell. It is clear that in these cases mitochondria ceases to perform its basic function.
Functions Mitochondria:
· Energy accumulation in the form of ATP,
· Depositing
· Synthetic (protein synthesis, hormones, amino acids).
Animals and man. The functions of this component of the cell of the cell are diverse and are mainly associated with synthesis, modification and transport
The endoplasmic network was first discovered in 1945. The American scientist K. Porter saw it with one of the first electrical microscopes. Since that time, its active research began.
There are two varieties of this organella in the cage:
- Granular, or rough endoplasmic network (covered with multiple ribosomes).
- Agranular, or smooth endoplasmic network.
Each type of reticulum has some features and performs completely different functions. Let's look at them in more detail.
Granular endoplasmic network: Building. This organella is a system of tanks, bubbles and tubules. Its walls consist of a bilipide membrane. The width of the cavity can fluctuate from 20 nm to several micrometers - everything depends on the secretory activity of the cell.
There are few specialized cells that are characterized by a low level of metabolism, EPS is represented by just a few separate tanks. Inside the cell that actively synthesizes the protein, the endoplasmic network consists of a plurality of tanks and a branched tubuine system.
As a rule, granular EPS through the tubules is associated with the membranes of a nuclear shell - this is exactly the complex processes of the synthesis and transport of protein molecules occur.
Granular endoplasmic network: functions. As already mentioned, the entire surface of the EPS from the cytoplasm side is covered with ribosomes, which are known to participate in the EPS - this is the place of synthesis and transport of protein compounds.
This organella is responsible for the synthesis of the cytoplasmic membrane. But in most cases, the protein molecules were created further using membrane bubbles are transported to where their further modification and distribution occurs, respectively, the needs of cells and tissues.
In addition, in the cavisters of the EPS tanks, some protein changes occur - for example, an attachment to it of a carbohydrate component. Here, by aggregation, large secretory granules are formed.
Agranular endoplasmic network: Building and functions. The structure of smooth EPS has some differences. For example, such an organella consists only of tanks and does not have the channel system. Such EPS complexes, as a rule, have smaller sizes, but the width of the tank, on the contrary, more.
The smooth endoplasmic network is not related to the synthesis of protein components, but executes a number of equally important functions. For example, it is here that the synthesis of steroid hormones occurs in a person and all vertebrate animals. That is why the volume of smooth EPS in adrenal cells is quite large.
The EPS liver cells produces the necessary enzymes that are involved in carbohydrate exchange, namely in the decay of glycogen. It is also known that hepatic cells are responsible for neutralizing toxins. In the tanks of this orgella, the synthesis of the hydrophilic component occurs, which is then attached to the toxic molecule, increases its solubility in the blood and urine. Interestingly, in hepatocytes that are constantly influenced by toxins (poisons, alcohol), almost the entire cell is engaged tightly located with a smooth EPS tank.
In muscle cells there is a special variety of smooth EPS - sarcoplasmatic reticulum. He acts as a calcium depot, regulating, thus, the processes of activity and peace of the cell.
As can be seen, the EPS functions are varied and very important for the normal functioning of a healthy cell.
The structure of the endoplasmic network
Definition 1.
Endoplasmic reticulum (EPS, endoplasmic reticulum) is a complex ultramicroscopic, very branched, interconnected membrane system, which more or less evenly permeates the mass of the cytoplasm of all eukaryotic cells.
EPS - membrane organelles, consisting of flat membrane bags - tanks, channels and tubes. Due to this structure, the endoplasmic network significantly increases the area of \u200b\u200bthe inner surface of the cell and divides the cell to the section. Inside it is filled matrix (moderately dense loose material (synthesis product)). The content of various chemicals in sections is not the same, because in the cell both simultaneously and in a certain sequence can occur various chemical reactions in a small amount of cells. The endoplasmic network opens in perinuclear space (The cavity between the two karyolem membranes).
The membrane of the endoplasmic network consists of proteins and lipids (mainly phospholipids), as well as enzymes: adenosinerphosphatases and enzymes of the synthesis of membrane lipids.
There are two types of endoplasmic network:
- Smooth (agranular, nuclear power plant), represented by tubes, which are analized between themselves and do not have on the surface of Ribosoma;
- Roughhouse (Granular, GRES), consisting also of the connected tanks, but they are covered with ribosomes.
Note 1.
Sometimes you allocate overgoing, or transient (TPP) The endoplasmic network, which is located in the transition site of one species of ES to another.
Granular ES is peculiar to all cells (except spermatozoa), but its degree of development is different and depends on the specialization of the cell.
GRES of epithelial gland cells (pancreas, producing digestive enzymes, liver - synthesizing albumin serums), fibroblasts (cells of connective tissue, producing collagen protein), plasma cells (production of immunoglobulins).
Agranular ES prevails in adrenal cells (synthesis of steroid hormones), in muscle cells (calcium exchange), in the cells of the base glands of the stomach (chlorine ions isolation).
Another type of EPS membranes are branched membrane tubes containing inside a large number of specific enzymes, and vesicles are small, surrounded membrane bubbles, mainly located next to the tubes and tanks. They ensure the transfer of those substances that are synthesized.
EPS functions
The endoplasmic network is a synthesis device and, partly, transport of substances of the cytoplasm, due to which the cell performs complex functions.
Note 2.
The functions of both types of EPS are associated with synthesis and vehicles. The endoplasmic network is a universal transport system.
Smooth and rough endoplasmic networks with their membranes and contents (matrix) perform general functions:
- separating (structuring), thanks to which the cytoplasm is ordered and is not mixed, as well as prevents random substances to the organella;
- transmembrane transport, due to which the transfer of the required substances through the membrane wall is carried out;
- the synthesis of the membrane lipids with the participation of enzymes contained in the membrane itself and ensuring the reproduction of the endoplasmic network;
- due to the difference in the potentials arising between the two surfaces of the ES membranes, it is possible to provide excitation pulses.
In addition, each of the varieties of the network is characterized by its specific functions.
Functions smooth (agranular) endoplasmic network
Agranular endoplasmic network, except for these functions common to both types of ES, is still characteristic of it only for it:
- calcium depot. In many cells (in skeletal muscles, in heart, egg cells, neurons), there are mechanisms that can change the concentration of calcium ions. Protective muscle tissue contains a specialized endoplasmic network called a sarcoplasmic reticulum. This is a calcium ion tank, and the membranes of this network contain powerful calcium pumps capable of throwing a large amount of calcium to cytoplasm or transport it in the network channel cavity for hundredths of seconds;
- synthesis lipid, substances like cholesterol and steroid hormones. Steroid hormones are synthesized mainly in endocrine cells of the sex glands and adrenal glands, in kidney and liver cells. Intestinal cells synthesize lipids, which are removed in lymph, and then into blood;
detoxification function - neutralization of єkzogenic and endogenous toxins;
Example 1.
In renal cells (hepatocytes) contains oxidase enzymes that can destroy the phenobarbital.
orgellary enzymes take part in synthesis glycogen (in liver cells).
Functions of a rough (granular) endoplasmic network
For the granular endoplasmic network, in addition to the general functions listed, specially characteristic:
- synthesis proteins GRES has some features. It begins on free polysomas, which are further associated with ES Fabrics.
- The granular endoplasmic network synthesizes: all cells of the cell membrane (except for some hydrophobic proteins, proteins of internal membranes of mitochondria and chloroplasts), specific proteins of the internal phase of membrane organelles, as well as secretory proteins that are transported through the cell and come into extracellular space.
- postranslation modification of proteins: Hydroxylation, Sulfatization, Phosphorillion. An important process is glycosylation that occurs under the action of glycosyltransprofrase enzymes associated with the enzyme membrane. Glycosylation occurs before the secretion or transport of substances to some cells of the cell (the Golgi complex, lysosomes or plasmolem).
- transportation substances on the intramaterial part of the network. Synthesized proteins in the gaps of the ES are moved to the Golgi complex, which displays the substance from the cell.
- thanks to the participation of the granular endoplasmic network the Golgi complex is formed.
The functions of the grainy endoplasmic network are associated with proteins transport, which are synthesized in ribosomes and are located on its surface. Synthesized proteins come inside EPS, twisted and acquired the tertiary structure.
Protein, which is transported to tanks, changes significantly on its path. It can, for example, phosphorylate or turn into a glycoprotein. The usual path for the protein is the path through the grainy EPS into the Golgji apparatus, from which it or comes out the outside of the cells, or goes to other organelles of the same cell, for example, to lysosomes), or postponed in the form of spare granules.
In liver cells, both a grainy and non-critical endoplasmic mesh take part in the detoxification processes of poisonous substances, which are then derived from the cell.
As well as the outer plasma membrane, the endoplasmic mesh has selective permeability, as a result of which the concentration of substances inside and outside the channels of the grid of non-etinakov. It matters for the cell function.
Example 2.
In the endoplasmic grid of muscle cells, more calcium ions than in its cytoplasm. Coming from the channels of the endoplasmic mesh, calcium ions start the process of cutting muscle fibers.
Education of the endoplasmic network
The lipid components of the membrane of the endoplasmic network are synthesized by the enzymes of the network itself, protein - comes from ribosomes located on its membranes. In a smooth (agranular) endoplasmic network, there are no own protein synthesis factors, because it is believed that this organella is formed as a result of the loss of ribosoma with a granular endoplasmic network.
