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Where the endoplasmic network is found. The structure and function of EPS. In the dontiomome there are two poles

Organly value organelles. Endoplasmic reticulum.

Orgella - constantly present in the cytoplasm of the structure specialized in performing certain functions in the cell. They are divided into organelles in common and special meaning.

The endoplasmic network, or endoplasmic reticulum, is a system of flat membrane tanks and membrane tubes. Membrane tanks and tubes are connected to each other and form a membrane structure with general contents. This allows you to isolate certain areas of the cytoplasm from the main nialoplasm and implement some specific cellular functions in them. As a result, the functional differentiation of various zones of cytoplasm occurs. The EPS membrane structure corresponds to a liquid-mosaic model. Morphologically distinguish 2 types of EPS: smooth (agranular) and rough (granular). Smooth EPS is represented by the membrane tube system. Rough EPS is a system of membrane tanks. On the outside of the membranes of roughing EPS are located ribosomes. Both types of EPS are in the structural dependence - the membrane of one type of EPS can switch to the membranes of another species.

Functional network features:

1.gramal EPS participates in the synthesis of proteins, complex protein molecules are formed in the canals.

2. Climbing EPS participates in the synthesis of lipids, carbohydrates.

3. Transport organic substances in a cage (via EPS channels).

4. Salid the cell per sections - in which various chemical reactions and physiological processes can be simultaneously going.

Smooth Eps. It is polyfunctional. In its membrane, there are proteins-0 embells that catalyze the synthesis reactions of membrane lipids. In smooth EPS, some non-membrane lipids (steroid hormones) are synthesized. The membrane of this type EPS includes Ca2 + carriers. They transport calcium on a concentration gradient (passive transport). For passive transport There is a synthesis of ATP. With their help in the smooth EPS, the concentration of CA2 + in hyaloplasm is regulated. This parameter is important for the regulation of the operation of microtubule and microfbrill. In muscle cells, smooth EPS regulates the muscles cut. The EPS takes detoxification of many harmful substances for the cell (drugs). Smooth EPS can form membrane bubbles, or microthel. Such bubbles carry out specific oxidative reactions isolated from EPS.

The main function rough EPS Is protein synthesis. This is determined by the presence of ribosomes on membranes. In the membrane, rough EPS has special riboforins proteins. Ribosomes interact with riboforins and fixed on the membrane in a certain orientation. All proteins synthesized in EPS have a terminal signal fragment. On ribosomes, the rough EPS is a synthesis of three types of proteins:

1. Membed proteins. All plasmolm proteins, membranes of the EPS itself and most of the proteins of other organoids are ribosome EPS products.

2.Cretor proteins. These proteins fall into the EPS cavity, and then by exocytosis are derived from the cell.

3.Strodorganoid proteins. These proteins are localized and operated in the cavities of membrane organoids: the EPS itself, the Golges complex, lysosomes, mitochondria. EPS participates in the formation of biomembrane.

In the tanks, a grinding EPS occurs a post-translation modification of proteins.

EPS is a universal eukaryotic cell organoid. Violation of the structure and function of the EPS leads to serious consequences. EPS is the place of formation of membrane bubbles with specialized features (peroxisoma).

Endoplasmic reticulum The EPR consists of an extensive network of tubes and pockets, surrounded by a membrane. The membrane area of \u200b\u200bthe endoplasmic reticulum is more than half of the total area of \u200b\u200ball cell membranes.

The EPR membrane is morphologically identical to the shell of the cell nucleus and is one whole with it. Thus, the cavities of the endoplasmic reticulum are opened in the intermambrane cavity of the nuclear shell. EPS membranes provide active transport of a number of elements against the concentration gradient. The threads forming the endoplasmic reticulum are in diameter 0.05-0.1 μm (sometimes up to 0.3 μm), the thickness of the two-layer membranes forming the canal wall is about 50 angstroms (5HM, 0.005 μm). These structures contain unsaturated phospholipids, as well as some amount cholesterol and sphingolipids. Their composition also includes proteins.

The tubes whose diameter ranges from 0.1-0.3 μm, filled with homogeneous content. Their function is the implementation of communication between the contents of the EPS bubbles, the outer medium and the core core.

Endoplasmic reticulum is not stable structure and susceptible to frequent changes.

Severe two types of EPR:

granular (grungy) endoplasmic reticulum;
agranular (smooth) endoplasmic reticulum.

On the surface of the granular endoplasmic reticulum there is a large number of ribosomes that are absent on the surface of the agranular EPR.

Granular and agranular endoplasmic reticulum perform various functions in the cell.

Smooth EPR Consists of membrane tubes, tubules, vacuoles. There are no ribosomes on his membranes. The degree of development of smooth EPR is non-etinakov both in different cells and inside a single cell. It is very labile and is capable of substantial restructuring under changing conditions. One of the most important functions of smooth EPR is synthesis lipid (including membrane). Therefore, it prevails in cells specializing in lipid metabolism. Smooth EPR activities also associate with metabolism of some intracellular polysaccharides, in particular with the synthesis of glycogen. In some cells, smooth EPR specializes in performing special functions. For example, in cells of adrenal cortexes in EPR, steroid hormones are synthesized. Here are enzymes that provide cholesterol synthesis and its transformation into steroid hormones. In hepatocytes, vertebrate smooth EPR specializes in detoxification of toxic substances. Smooth EPR is greatly growing. After removal of toxic substances, the excess network is destroyed by an autophagic path. In transverse muscles, smooth EPR performs a function calcium ions deposit.

To hormones, which are formed in the agranular EPS, belong, for example, sex hormones of vertebrate animals and steroid hormones of adrenal glands. The cells of the testicles and ovaries responsible for the synthesis of hormones contain a large amount of agranular endoplasmic reticulum.

Carbohydrates in the body accumulate in the liver in the form of glycogen. By means of glycogenolysis, glycogen in the liver is transformed into glucose, which is an essential process in maintaining blood glucose levels. One of the enzymes of agranular EPR splits from the first product of glycogenolysis, glucose-6-phosphate, phosphogroup, thus allowing glucose to leave the cell and increase the level of sugars in the blood.

The smooth endoplasmic reticulum of liver cells is actively involved in neutralization of all sorts of poisons. The smooth EPR enzymes attach hydrophilic radicals to the toxic substances molecules, as a result of which the solubility of toxic substances in the blood and urine increases, and they are faster from the body. In case of continuous receipt of poisons, medicines or alcohol is formed large quantity Agranular EPR, which increases the dose of the active substance necessary to achieve the previous effect.

Concentration of ions Calcium in EPS can reach 10-3 mol, while in cytozela is about 10-7 mol (at rest). Under the action of inositatrimphosphate and some other incentives, calcium is released from EPS by light diffusion. Return calcium in EPS is provided by active transport. At the same time, the EPS membrane provides an active transfer of calcium ions against gradients of the concentration of large orders. And the reception, and the release of calcium ions in EPS is in a subtle interconnection with physiological conditions.

The concentration of calcium ions in cytozol affects the set of intracellular and intercellular processes, such as activation or inactivation of enzymes, gene expression, synaptic plasticity of neurons, muscle contraction, the release of antibodies from the cells of the immune system.

A special form of agranular endoplasmic reticulum, sarpoplasmatic reticulumis an EPU in muscle cells in which calcium ions are actively pumped from the cytoplasm in the EPR cavity against the concentration gradient in the non-excited state of the cell and are exempted into the cytoplasm to initiate a reduction.

Also, the smooth EPS synthesizes the provaculations necessary for the life of the plant cell.

Endoplasmic reticulum (network).
Endoplasmic reticulum - network of channels, tubes, bubbles, tanks located inside the cytoplasm.
Structure.
It is a system of membranes having an ultramicroscopic structure (diameter of tubes 25-75 nm). The entire network has the same structure as the outer cell membrane of the nuclear shell and is combined into a single integer with it. These structures contain unsaturated fats, as well as some cholesterol and other complex fats as well as proteins.
The endoplasmic reticulum is not a stable structure and are subject to frequent changes.
Two types of endoplasmic reticulum are distinguished:
granular endoplasmic reticulum;

agranular(smooth) endoplasmic reticulum.

On the surface of the granular endoplasmic reticulum there is a large number of ribosomes that are absent on the surface of the agranular endoplasmic reticulum.
Granular and agranular endoplasmic reticulum perform various functions in the cell.
Functions.
Agranular EPR.
Agranular endoplasmic reticulum participates in many metabolic processes. Also, the agranular endoplasmic reticulum plays an important role in carbohydrate exchange, neutralization of calcium poisons and stocking. The enzymes of the agranular endoplasmic reticulum participate in the synthesis of various fats and complex fats, fatty acids and steroids. In particular, in connection with this, agranular endoplasmic reticulum prevails in the cells of adrenal and liver.
1) Synthesis of hormones
To hormones that are formed in agranular EPS belong, for example, sex hormones of vertebrate animals and steroid hormones of adrenal glands. The cells of the testicles and ovaries responsible for the synthesis of hormones contain a large amount of agranular endoplasmic reticulum.
2) accumulation and conversion of carbohydrates
Carbohydrates in the body accumulate in the liver in the form of glycogen.
Glycogen- the main stock of human and animal carbohydrates.
By means of glycolysis (glucose cleavage in cells), glycogen in the liver is transformed into glucose, which is an essential process in maintaining blood glucose levels. One of the agranular EPS enzymes rolls off from the first product of glycolysis, glucose-6-phosphate, phosphogroup, thus allowing glucose to leave the cell and increase the level of sugars in the blood.
3) neutralization of poisons
The smooth endoplasmic reticulum of liver cells is actively involved in neutralizing all sorts of poisons. The smooth EPR enzymes attach to the molecules of toxic substances by water-cutting radicals, as a result of which the solubility of toxic substances in the blood and urine increases, and they are faster from the body. In the case of continuous admission of poisons, medicines or alcohol, a larger amount of agranular EPR is formed, which increases the dose of the active substance necessary to achieve the previous effect.
4) the role of EPS as a calcium depot
The concentration of calcium ions in the endoplasmic network can reach 10-3 mol, while in the cytoplasm is about 10-7 mol (at rest). Under the action of inositatriphosphate (participates in signal transmission in the cell) and some other calcium incentives are released from EPS by light diffusion. Return calcium in EPS is provided by active transport (more here). At the same time, the EPS membrane provides an active transfer of calcium ions against gradients of the concentration of large orders. And the reception, and the release of calcium ions in EPS is in a subtle interconnection with physiological conditions.
5) sarcoplasmic reticulum
The special form of agranular endoplasmic reticulum, sarcoplasmic reticulum, is an EPS in muscle cells in which calcium ions are actively pumped from the cytoplasm in the EPR cavity against the concentration gradient in the non-excited state of the cell and are released into a cytoplasm to initiate a reduction.
Granular EPR.
The granular endoplasmic reticulum has two functions: protein synthesis and membranes.
1) protein synthesis
The proteins produced by the cell are synthesized on the surface of the ribosoma, which can be attached to the surface of the EPS. The resulting polypeptide chains are placed in the cavity of the granular endoplasmic reticulum (where polypeptide chains are also included in the cytoplasm), where they are subsequently cropped and folded. Thus, linear sequences of amino acids are obtained after transfer to the endoplasmic retisculum necessary three-dimensional structure, after which they are re-moved to the cytoplasm.
2) synthesis membranes
The production of EPR phospholipids expands its own membrane surface, which, by means of transport vesicles, sends membrane fragments to other parts of the membrane system.
3D model EPR
Some description

Cells representing a branched system from the surrounded membrane of the flattened cavities, bubbles and tubules.

Schematic representation of the cell kernel, an endoplasmic reticulum and a Golgi complex.
(1) Cell core.
(2) Pores of the nuclear membrane.
(3) Granular endoplasmic reticulum.
(4) Agranular endoplasmic reticulum.
(5) Ribosomes on the surface of the granular endoplasmic reticulum.
(6) Transported proteins.
(7) Transport vesicles.
(8) Golgi complex.
(9)
(10)
(11)

History opening

For the first time, the endoplasmic reticulum was discovered by American scientist K. Porter in 1945 through electron microscopy.

Structure

The endoplasmic reticulum consists of an extensive network of tubes and pockets, surrounded by a membrane. The membrane area of \u200b\u200bthe endoplasmic reticulum is more than half of the total area of \u200b\u200ball cell membranes.

The EPR membrane is morphologically identical to the shell of the cell nucleus and is one whole with it. Thus, the cavities of the endoplasmic reticulum are opened in the intermambrane cavity of the nuclear shell. EPS membranes provide active transport of a number of elements against the concentration gradient. The threads that form the endoplasmic reticulum are in diameter 0.05-0.1 μm (sometimes up to 0.3 μm), the thickness of the two-layer membranes, forming the canal wall of about 50 angstroms (5 Nm, 0.005 μm). These structures contain unsaturated phospholipids, as well as a certain amount of cholesterol and sphingolipids. They also include proteins.

The endoplasmic reticulum is not a stable structure and are subject to frequent changes.

Severe two types of EPR:

granular endoplasmic reticulum
agranular (smooth) endoplasmic reticulum

On the surface of the granular endoplasmic reticulum there is a large number of ribosomes that are absent on the surface of the agranular EPR.

Granular and agranular endoplasmic reticulum perform various functions in the cell.

Functional functions of the endoplasmic reticulum

With the participation of the endoplasmic reticulum, the transmission and transport of proteins, synthesis and transport of lipids and steroids occur. The EPS is also characterized by the accumulation of synthesis products. The endoplasmic reticulum takes part in the creation of a new nuclear shell (for example, after mitosis). The endoplasmic reticulum contains intracellular calcium supply, which is, in particular, the mediator of a reduction in the muscle cell. In the cells of muscle fibers there is a special form of the endoplasmic reticulum - sarpoplasmatic network.

Agranular endoplasmic reticulum functions

Agranular endoplasmic reticulum participates in many metabolic processes. The enzymes of agranular endoplasmic reticulum participate in the synthesis of various lipids and phospholipids, fatty acids and steroids. Also, the agranular endoplasmic reticulum plays an important role in carbohydrate metabolism, cell disinfecting and calcium stocking. In particular, in connection with this, agranular endoplasmic reticulum prevails in the cells of adrenal and liver.

Synthesis Gormonov

To hormones that are formed in agranular EPS belong, for example, sex hormones of vertebrate animals and steroid hormones of adrenal glands. The cells of the testicles and ovaries responsible for the synthesis of hormones contain a large amount of agranular endoplasmic reticulum.

Accumulation and conversion of carbohydrates

Carbohydrates in the body accumulate in the liver in the form of glycogen. By means of glycolysis, glycogen in the liver is transformed into glucose, which is an essential process in maintaining blood glucose levels. One of the agranular EPS enzymes rolls off from the first product of glycolysis, glucose-6-phosphate, phosphogroup, thus allowing glucose to leave the cell and increase the level of sugars in the blood.

Neutralization of poison

The smooth endoplasmic reticulum of liver cells is actively involved in neutralizing all sorts of poisons. The smooth EPR enzymes join the metals of active substances molecules that can thus be dissolved faster. In the case of continuous receipt of poisons, medicines or alcohol, a larger amount of agranular EPR is formed, which increases the dose of the active substance necessary to achieve the previous effect.

Sarpoplasmatic reticulum

The special form of agranular endoplasmic reticulum, sarcoplasmic reticulum, forms EPS in muscle cells, in which calcium ions are actively pumped from the cytoplasm in the EPR cavity against the concentration gradient in the non-excited state of the cell and are exempted into the cytoplasm to initiate a reduction. The concentration of calcium ions in the EPS can reach 10 -3 mol, while in cytosol about 10 -7 mol (at rest). Thus, the sarcoplasmic reticulum membrane provides active transfer against the gradients of the concentration of large orders. And the reception and release of calcium ions in the EPS is in a subtle interconnection against physiological conditions.

The concentration of calcium ions in the cytosol affects the set of intracellular and intercellular processes, such as: activation or braking enzymes, gene expression, synaptic plasticity of neurons, reduce muscle cells, exemption of antibodies from the cells of the imune system.

Granular endoplasmic reticulum functions

The granular endoplasmic reticulum has two functions: protein synthesis and membranes.

Synthesis proteins

The proteins produced by the cell are synthesized on the surface of the ribosoma, which can be attached to the surface of the EPS. The obtained polypeptide chains are placed in the cavity of the granular endoplasmic reticulum (where the polypeptide chains are and synthesized in cytosole), where they are subsequently cut and folded correctly. Thus, linear sequences of amino acids are obtained after translocation to the endoplasmic reticulum necessary three-dimensional structure, after which they are re-moved to cytosol.

Synthesis membranes

The ribosomes attached to the surface of the granular EPR produce proteins that, along with the production of phospholipids, among other things, expand its own EPR membrane surface, which, by means of transport vesicles, sends membrane fragments to other parts of the membrane system.

Structure

This is an extensive maze from the channels, cavities, visa, "tanks", which are closely related and communicated to each other. This organoid is covered with a membrane that is reported both with cytoplasm and cellular outdoor membrane. The volume of cavities is different, but they all contain a homogeneous liquid that allows the interaction between the core of the cell and the external environment. Sometimes there are branches from the main network in the form of single bubbles. The rough EPS differs from a smooth presence on the outer surface of a large amount of ribosomes.

Functions

Agranular EPS functions. It takes part in the formation of steroid hormones (for example, in adrenal cortex cells). EPS contained in liver cells, participates in the destruction of some hormones, medicinal preparations and harmful substances, and in glucose transformation processes, which is formed from glycogen. Also, the agranular network produces phospholipids necessary for the construction of membranes of all types of cells. And in the reticulum of muscle tissue cells, calcium ions are deposited necessary to reduce muscles. This type of smooth endoplasmic network is differently called sarcoplasmic reticulum.
Granular EPS functions. First of all, the production of proteins occurs in granular reticulum, which will be subsequently removed from the cell (for example, the synthesis of products for the secretion of ferrous cells). And also in the roughing EPS, the synthesis and the assembly of phospholipids and multi-track proteins are used, which are then transported to the Golgi apparatus.
Common functions, both for a smooth endoplasmic reticulum, and for rough, is a distinctive function. Due to these organoids, the cell is divided into compartments (compartments). And additionally, these organelles are conveyors of substances from one part of the cell to another.