Golgi apparatus (Golgi complex) - AG

The structure known today as complex or Golgi apparatus (AG) first discovered in 1898 by the Italian scientist Camillo Golgi

It was possible to study in detail the structure of the Golgi complex much later using an electron microscope.

AG is a stack of flattened "tanks" with widened edges. A system of small one-membrane bubbles (Golgi bubbles) is associated with them. Each stack usually consists of 4-6 "cisterns", is a structural and functional unit of the Golgi apparatus and is called a dictyosome. The number of dictyosomes in a cell ranges from one to several hundred.

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

Golgi complex

Left - in a cage, among other organelles.

On the right - the Golgi complex with membrane vesicles separating from it

All substances synthesized on EPS membranes carried over to Golgi complex in membrane vesicles, which bud off from the EPS and then merge with the Golgi complex. The incoming organic matter from EPS undergoes further biochemical transformations, accumulates, and is packed into membrane vesicles and delivered to the places in the cage where they are needed. They are involved in the completion cell membrane or stand out outward ( secreted) from the cell.

Functions of the Golgi apparatus:

1 Participation in the accumulation of products synthesized in endoplasmic reticulum, in their chemical restructuring and maturation. In the tanks of the Golgi complex, the synthesis of polysaccharides takes place, their complexation with protein molecules.

2) Secretory - the formation of finished secretory products that are removed outside the cell by exocytosis.

3) Renewal of cell membranes, including areas of the plasmolemma, as well as replacement of plasma membrane defects in the process of cell secretory activity.

4) Place of formation of lysosomes.

5) Transport of substances

Lysosomes

The lysosome was discovered in 1949 by C. de Duve ( Nobel Prize for 1974).

Lysosomes- one-membrane organelles. They are small bubbles (diameter from 0.2 to 0.8 microns) containing a set of hydrolytic enzymes - hydrolases. The lysosome can contain 20 to 60 different types hydrolytic enzymes (proteinases, nucleases, glucosidases, phosphatases, lipases, etc.) that break down various biopolymers. The breakdown of substances using enzymes is called lysis (lysis-disintegration).

Lysosomal enzymes are synthesized on a rough EPS, transferred to the Golgi apparatus, where they are modified and packaged into membrane vesicles, which, after being separated from the Golgi apparatus, become lysosomes proper. (Lysosomes are sometimes called the "stomachs" of the cell)

Lysosome - membrane vesicle containing hydrolytic enzymes

Functions of lysosomes:

1. Degradation of substances absorbed as a result of phagocytosis and pinocytosis. Biopolymers are broken down to monomers, which enter the cell and are used for its needs. For example, they can be used to synthesize new organic matter or may undergo further degradation to generate energy.

2. Destroy old, damaged, excess organelles. The destruction of organelles can also occur during cell starvation.

3. Carry out autolysis (self-destruction) of cells (liquefaction of tissues in the area of ​​inflammation, destruction of cartilage cells during the formation of bone tissue, etc.).

Autolysis - This self-destruction cells resulting from the release of contents lysosomes inside the cell. Thanks to this, lysosomes are jokingly called "Instruments of suicide." Autolysis is a normal phenomenon of ontogenesis, it can spread both to individual cells and to the entire tissue or organ, as it happens during the resorption of the tadpole tail during metamorphosis, i.e., when the tadpole turns into a frog

Endoplasmic reticulum, Golgi apparatus and lysosomesform single vacuolar cell system, individual elements which can transform into each other during restructuring and changing the function of membranes.

Mitochondria

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

In shape, mitochondria can be rod-shaped, rounded, spiral, cupped, branched. The length of mitochondria ranges from 1.5 to 10 microns, the diameter is from 0.25 to 1.00 microns. The number of mitochondria in a cell can reach several thousand and depends on the metabolic activity of the cell.

The mitochondrion is limited two membranes ... The outer membrane of mitochondria is smooth, the inner membrane forms numerous folds - crista. Crystals increase the surface area of ​​the inner membrane. The number of cristae in mitochondria can vary depending on the cell's energy requirements. It is on the inner membrane that numerous enzyme complexes are concentrated that participate in the synthesis of adenosine triphosphate (ATP). Here is the energy chemical bonds converts into energy-rich (high-energy) ATP bonds ... Besides, in the mitochondria, the breakdown of fatty acids and carbohydrates takes place with the release of energy, which is accumulated and used for the processes of growth and synthesis The internal environment of these organelles is called matrix... It contains circular DNA and RNA, small ribosomes. It is interesting that mitochondria are semi-autonomous organelles, since they depend on the functioning of the cell, but at the same time they can maintain a certain independence. So, they are able to synthesize their own proteins and enzymes, as well as reproduce on their own (mitochondria contain their own DNA chain, which contains up to 2% of the DNA of the cell itself).

Mitochondrial functions:

1. Conversion of the energy of chemical bonds into high-energy ATP bonds (mitochondria are the "power stations" of the cell).

2. Participate in the processes of cellular respiration - oxygen breakdown of organic substances.

Ribosomes

Ribosome structure:
1 - large subunit; 2 - small subunit.

Ribosomes - non-membrane organelles, about 20 nm in diameter. Ribosomes consist of two fragments - a large and a small subunit. Chemical composition ribosomes - proteins and rRNA. RRNA molecules make up 50–63% of the ribosome mass and form its structural framework.

During protein biosynthesis, ribosomes can "work" singly or combine into complexes - polyribosomes (polysomes)... In such complexes, they are linked to each other by one mRNA molecule.

Subunits of ribosomes are formed in the nucleolus. Having passed through the pores in the nuclear envelope, ribosomes enter the membranes of the endoplasmic reticulum (EPS).

Ribosome function: assembly of the polypeptide chain (synthesis of protein molecules from amino acids).

Cytoskeleton

Cellular cytoskeleton is formed microtubules and microfilaments .

Microtubules are cylindrical formations with a diameter of 24 nm. Their length is 100 μm-1 mm. The main component is a protein called tubulin. It is unable to contract and can be destroyed by colchicine.

Microtubules are located in the hyaloplasm and perform the following function:

Create elastic, but at the same time strong frame cells, which allows her to maintain shape;

· Take part in the process of distribution of cell chromosomes (form a spindle of division);

· Provide movement of organelles;

Microfilaments- filaments that are located under the plasma membrane and consist of the protein actin or myosin. They can contract, resulting in the movement of the cytoplasm or protrusion of the cell membrane. In addition, these components are involved in the formation of constrictions during cell division.

Cell center

The cell center is an organoid consisting of 2 small granule centrioles and a radiant sphere around them - the centrosphere. The centriole is a cylindrical body 0.3-0.5 microns long and about 0.15 microns in diameter. The walls of the cylinder consist of 9 parallel tubes. The centrioles are arranged in pairs at right angles to each other. The active role of the cell center is found during cell division. Before cell division, centrioles diverge to opposite poles, and a daughter centriole appears near each of them. They form a spindle of division, which contributes to an even distribution of genetic material between daughter cells.

Centrioles belong to self-reproducing organelles of the cytoplasm, they arise as a result of duplication of existing centrioles.

Functions:

1. Ensuring a uniform divergence of chromosomes to the poles of the cell during mitosis or meiosis.

2. Center for the organization of the cytoskeleton.

Organelles of movement

Not present in all cells

Organoids of movement include cilia, as well as flagella. These are miniature hair-like outgrowths. The flagellum contains 20 microtubules. Its base is located in the cytoplasm and is called the basal body. The length of the flagellum is 100 µm or more. Flagella, which have only 10-20 microns, are called cilia ... When the microtubules slide, the cilia and flagella are able to vibrate, causing the cell itself to move. The cytoplasm may contain contractile fibrils called myofibrils. Myofibrils, as a rule, are located in myocytes - cells of muscle tissue, as well as in the cells of the heart. They are composed of smaller fibers (protofibrils).

In animals and humans cilia they cover the air Airways and helps to get rid of fine particulate matter such as dust. In addition, there are also pseudopods, which provide amoeboid movement and are elements of many unicellular and animal cells (for example, leukocytes).

Functions:

Specific

Core. Chromosomes

Structure

The Golgi complex is a stack of disc-shaped membrane sacs (cisterns), somewhat expanded closer to the edges, and a system of Golgi vesicles associated with them. A number of separate stacks (dictyosomes) are found in plant cells; animal cells often contain one large or several stacks connected by tubes.

In the Golgi Complex, there are 3 sections of cisterns surrounded by membrane vesicles:

1. Cis department (closest to the nucleus);
2. Medial department;
3. Trans department (the most distant from the core).

These departments differ in a set of enzymes. In the cis-department, the first cistern is called the "salvage cistern", since with its help the receptors coming from the intermediate endoplasmic reticulum are returned back. Enzyme of the cis-department: phosphoglycosidase (attaches phosphate to a carbohydrate - mannase). In the medial section there are 2 enzymes: mannazidase (cleaves off mannase) and N-acetylglucosamine transferase (adds certain carbohydrates - glycosamines). In the trans section there are enzymes: peptidase (proteolysis) and transferase (transfers chemical groups).

Functions

1. Segregation of proteins into 3 streams:
   • lysosomal - glycosylated proteins (with mannose) enter the cis-section of the Golgi complex, some of them are phosphorylated, a marker of lysosomal enzymes is formed - mannose-6-phosphate. In the future, these phosphorylated proteins will not undergo modification, but will enter the lysosomes.
   • constitutive exocytosis (constitutive secretion). This flow includes proteins and lipids, which become components of the surface apparatus of the cell, including the glycocalyx, or they can be part of the extracellular matrix.
   • Induced secretion - proteins that function outside the cell, the surface apparatus of the cell, in the internal environment of the body get here. It is characteristic of secretory cells.
2. Formation of mucous secretions - glycosaminoglycans (mucopolysaccharides)
3. Formation of carbohydrate components of the glycocalyx - mainly glycolipids.
4. Sulfation of carbohydrate and protein components of glycoproteins and glycolipids
5. Partial proteolysis of proteins - sometimes due to this, an inactive protein turns into an active one (proinsulin turns into insulin).

Transport of substances from the endoplasmic reticulum

The Golgi apparatus is asymmetric - cisterns located closer to the cell nucleus ( cis-Golgi) contain the least mature proteins, membrane vesicles, vesicles budding from the granular endoplasmic reticulum (EPR), on the membranes of which ribosomes synthesize proteins, are continuously attached to these cisterns. The transfer of proteins from the endoplasmic reticulum (EPS) to the Golgi apparatus occurs indiscriminately, however, incompletely or incorrectly folded proteins remain in the EPS. The return of proteins from the Golgi apparatus to EPS requires a specific signal sequence (lysine-asparagine-glutamine-leucine) and occurs due to the binding of these proteins to membrane receptors in the cis-Golgi.

Protein modification in the Golgi apparatus

In the cisterns of the Golgi apparatus, proteins intended for secretion, transmembrane proteins of the plasma membrane, proteins of lysosomes, etc. mature. The maturing proteins sequentially move along the cisterns to organelles, in which their modifications occur - glycosylation and phosphorylation. In O-glycosylation, complex sugars are attached to proteins through the oxygen atom. During phosphorylation, the phosphoric acid residue is attached to the proteins.

Different cisterns of the Golgi apparatus contain different resident catalytic enzymes and, therefore, different processes occur with maturing proteins in them. It is clear that such a stepwise process must somehow be controlled. Indeed, maturing proteins are “marked” with special polysaccharide residues (mainly mannose), apparently playing the role of a kind of “quality mark”.

It is not completely clear how the maturing proteins move along the cisterns of the Golgi apparatus, while the resident proteins remain more or less associated with one cistern. There are two mutually non-exclusive hypotheses explaining this mechanism:

• according to the first, the transport of proteins is carried out using the same mechanisms of vesicular transport as the pathway of transport from the ER, and the resident proteins are not included in the budding vesicle;
• according to the second, there is a continuous movement (maturation) of the cisterns themselves, their assembly from vesicles from one end and disassembly from the other end of the organelle, and the resident proteins move retrogradely (in the opposite direction) using vesicular transport.

Transport of proteins from the Golgi apparatus

In the end from trance-Golgi vesicles are budded containing fully mature proteins. The main function of the Golgi apparatus is to sort the proteins passing through it. In the Golgi apparatus, a "three-way protein flow" is formed:

• maturation and transport of plasma membrane proteins;
• maturation and transport of secrets;
• maturation and transport of lysosome enzymes.

With the help of vesicular transport, proteins passed through the Golgi apparatus are delivered "to the address" depending on the "marks" they received in the Golgi apparatus. The mechanisms of this process are also not fully understood. It is known that the transport of proteins from the Golgi apparatus requires the participation of specific membrane receptors, which recognize the "load" and ensure selective docking of the vesicle with one or another organelle.

Lysosome formation

All hydrolytic enzymes of lysosomes pass through the Golgi apparatus, where they receive a "label" in the form of a specific sugar - mannose-6-phosphate (M6P) - as part of their oligosaccharide. The attachment of this label occurs with the participation of two enzymes. The enzyme N-acetylglucosamine phosphotransferase specifically recognizes lysosomal hydrolases by the details of their tertiary structure and attaches N-acetylglucosamine phosphate to the sixth atom of several mannose residues of the hydrolase oligosaccharide. The second enzyme, phosphoglycosidase, cleaves off N-acetylglucosamine, creating an M6F-tag. Then this label is recognized by the M6F receptor protein, with its help the hydrolases are packed into vesicles and delivered to the lysosomes. There, in an acidic environment, phosphate is cleaved from the mature hydrolase. When N-acetylglucosamine phosphotransferase malfunctions due to mutations or genetic defects in the M6F receptor, all lysosomal enzymes are delivered to the outer membrane by default and secreted into the extracellular environment. It turned out that, normally, a certain number of M6F receptors also enter the outer membrane. They return accidentally hit external environment enzymes of lysosomes inside the cell during endocytosis.

Transport of proteins to the outer membrane

As a rule, even during the synthesis, the proteins of the outer membrane are incorporated by their hydrophobic sections into the membrane of the endoplasmic reticulum. Then, as part of the vesicle membrane, they are delivered to the Golgi apparatus, and from there to the cell surface. When the vesicle fuses with the plasmalemma, such proteins remain in its composition, and are not released into the external environment, like those proteins that were in the vesicle cavity.

Secretion

Almost all substances secreted by the cell (both protein and non-protein nature) pass through the Golgi apparatus and are packed into secretory vesicles there. So, in plants, with the participation of dictyosomes, material is secreted

The Golgi apparatus, also called the Golgi complex, is found in both animals and animals and is usually made up of a collection of membrane-shaped cup-shaped sections called cisterns that look like a stack of deflated balloons.

However, some unicellular flagellates have 60 cisterns that form the Golgi apparatus. Likewise, the number of stacks of the Golgi complex in varies depending on its functions. usually contain from 10 to 20 stacks per cell, combined into one complex by tubular connections between tanks. The Golgi apparatus is usually located close to.

Discovery history

Due to the relatively large sizes the Golgi complex was one of the first organelles observed in cells. In 1897, an Italian physician named Camillo Golgi studying nervous system, used new technology coloring, which he himself developed (and which is relevant today). Thanks to the new method, the scientist was able to discern the cellular structure and called it the internal reticular apparatus.

Soon after he publicly announced his discovery in 1898, the structure was named after him, becoming universally known as the Golgi apparatus. However, many scientists of the time did not believe that the Golgi observed a real cell organelle, and attributed the scientist's discovery to a visual distortion caused by staining. The invention of the electron microscope in the twentieth century conclusively confirmed that the Golgi apparatus is a cellular organelle.

Structure

In most eukaryotes, the Golgi apparatus is formed from stacks of sacs, consisting of two main sections: the cis section and the trans section. The cis compartment is a complex of flattened membrane discs known as cisterns, derived from vesicular clusters that rush out of the endoplasmic reticulum.

Mammalian cells typically contain 40 to 100 stacks. Typically, each stack contains 4 to 8 tanks. However, some have about 60 cisterns. This set of cisterns is subdivided into cis, medial, and trans sections. The trans section is the terminal cisternal structure from which proteins are packed into vesicles destined for lysosomes, secretory vesicles, or the cell surface.

Functions

The Golgi apparatus is often considered the distribution and delivery department chemical substances cells. It modifies proteins and lipids (fats) that are produced in, and prepares them for export outside the cell or for transport to other locations within the cell. Proteins and lipids built in the smooth and rough endoplasmic reticulum are packed into tiny vesicular vesicles that move through until they reach the Golgi complex.

The vesicles fuse with the Golgi membranes and release the contained molecules into the organelle. Once inside, the compounds are further processed by the Golgi apparatus and then guided in the vesicle to their destination inside or outside the cell. Exported products represent the secretion of proteins or glycoproteins, which are part of the cell's function in the body. Other substances return to the endoplasmic reticulum or may mature to become.

The molecular modifications that take place in the Golgi complex occur in an orderly manner. Each cistern has two main sections: the cis section, which is the end of the organelle, where substances come from the endoplasmic reticulum for processing, and the trans section, where they exit in the form of smaller individual vesicles. Consequently, the cis-section is located near the endoplasmic reticulum, from where most of the substances come, and the trans-section is located near the cell, where many of the substances that are modified in the Golgi apparatus are sent.

The chemical composition of each compartment, as well as the enzymes contained in the lumens (internal open spaces of the cisterns) between the compartments, are distinctive. Proteins, carbohydrates, phospholipids and other molecules formed in the endoplasmic reticulum are transferred to the Golgi apparatus to undergo biochemical modification during the transition from the cis to trans sections of the complex. Enzymes present in the Golgi lumen modify the carbohydrate moiety of glycoproteins by adding or subtracting individual sugar monomers. In addition, the Golgi apparatus itself produces a wide variety of macromolecules, including polysaccharides.

The Golgi complex in plant cells produces pectins and other polysaccharides necessary for plant structure and metabolism. Products exported by the Golgi apparatus through the trans section ultimately fuse with the cell's plasma membrane. Among the most important functions of the complex is sorting a large number macromolecules produced by the cell and their transportation to the required destinations. Specialized molecular identification labels or labels such as phosphate groups are added by Golgi enzymes to aid in this sorting process.

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The Golgi complex or apparatus was discovered in 1898 by Camillo Golgi. The apparatus itself is a polymorphic, asymmetric structure in the composition of the cell, which is disk-shaped cisterns stacked in stacks. Another formation is associated with these cisterns - the Golgi bubbles, which come to the cisterns and merge with them. Then, in another section, the vesicles bud off from the complex. Vesicles are otherwise called vesicles.

In plant and animal cells, anatomically, the Golgi apparatus looks differently:

• In animal cells, there is one large stack of cisterns, sometimes several stacks of cisterns connected by tube-like structures;
• In plant cells, it is represented by the so-called dictyosomes. Dictyosomes are separate complexes of cisterna stacks with vesicle vesicles. Dictyosomes are present not only in plant cells, but also in the cells of a number of protozoan invertebrates. In dictyosomes, polysaccharide complexes are produced, which are involved in the construction of plant cell walls. Some scientists believe that dictyosomes also have a function in the construction of vacuoles. They argue that vacuoles are formed by swelling of the intermembrane space of the dictyosomes themselves. It is known that the vacuole in a plant cell occupies a large part of it.

The structure of the apparatus can be conditionally divided into three sections:

1. The cis section is an asymmetric initial section with an immature protein.
2. Middle department. Otherwise, it is also called the medial section.
3. Trans department. This is the matured protein complex section. Here, bubbles form and leave, carrying already fully formed mature proteins.

Transport of substances from EPS

The Golgi apparatus performs the function transport of substances from the endoplasmic reticulum... The asymmetric part of the apparatus is closer to the nucleus and contains immature proteins. Bubbles come up here regularly. The entry of proteins from the endoplasmic reticulum into the apparatus is not very selective, but proteins with an irregular structure do not penetrate into the apparatus.

In the presence of a special signaling amino acid sequence, the reverse transport of proteins from the apparatus to the EPS occurs.

Protein conversion

In the bags of the Golgi complex protein conversion function... Here proteins for secretion, transmembrane and complexes that make up lysosomes ripen.

The stacks of cisterns contain a different set of enzymes that catalyze protein conversion processes: proteins pass from one cistern to another and undergo various enzymatic catalytic conversions. How the transition of proteins from one cistern to another is carried out is not fully understood. This is the subject of biochemistry. This is where the most difficult chemical reactions with the participation of receptors.

Having passed the tank system of the apparatus, the protein enters the trans section. Bubbles filled with the formed protein begin to gradually separate from it. It must be said that each protein is transported to the organelle for which it was created. In the Golgi apparatus, proteins acquire a kind of receptor label, thanks to which the transport system recognizes the protein and transfers it to the destination for which it was created.

Conventionally, the trans department produces proteins of three directions:

1. Lysosomal enzymes are a group of substances that are sent to lysosomes.
2. Proteins for membrane building.
3. Secrets.

Lysosome formation

One of the streams of the three-directional movement of protein - this is the formation of lysosomes... Vesicles-vesicles depart from the trans-section of the Golgi apparatus, which carry enzymes to the organelle - the lysosome. Lysosome is a formation from merged vesicles that has an acidic reaction and a set of autolytic enzymes. Lysosomes perform a number of important functions in the cell:

• Digestion of foreign particles and cells, including bacteria, captured during endocytosis.
• Autophagy - translated into Russian - "self-eating". Despite the terrible name - this is a very useful function - lysis and dissolution into elementary components of dying organelles. Replacement of aging structures with new ones.
• Autolysis is the process of self-destruction of cells. Complex process of cascade reactions. A striking example of autolysis is the process of transformation of a tadpole into a frog. As you know, a tadpole has a tail, but an adult frog does not. At the later stages of development in the tadpole, the tail gradually decreases and disappears altogether. This is due to the fact that the processes of autolysis of cells actively occur at the base of the tail. The cells are destroyed, and their nutritional components are absorbed and go to build the animal's body.

Secretion

Many secrets of the cellular structure mature in the Golgi apparatus... These are components of a protein nature and also non-protein components. From here they are transported to all areas of the cells. The secretion scheme is as follows: proteins synthesized in the endoplasmic reticulum enter the Golgi apparatus through a special compartment. Vesicles are budded from the Golgi apparatus from the trans section, which carry components to the organelles and outside the cell.

Components outside the cell pass through the membrane by exocytosis transfer. The visicle, approaching the membrane, is embedded in it and opens its contents on the opposite side of the cell. As a result, all contents are outside the cell. In this case, there is a double benefit - transfer of components and completion of the membrane.

Video

This video will help you understand the structure of the cell and what the Golgi complex is.

Golgi complex is a stack of disc-shaped membrane sacs (cisterns), somewhat expanded closer to the edges, and the associated Golgi vesicle system. A number of separate stacks (dictyosomes) are found in plant cells; animal cells often contain one large or several stacks connected by tubes.

1. Accumulates and removes organic substances synthesized in the endoplasmic reticulum

2. Forms lysosomes

3. Formation of carbohydrate components of the glycocalyx - mainly glycolipids.

Lysosomes are an integral part of the composition of the cell. They are a type of vesicle. These cellular assistants, being part of the vacuome, are covered with a membrane and filled with hydrolytic enzymes. The importance of the existence of lysosomes inside the cell is provided by the secretory function, which is necessary in the process of phagocytosis and autophagocytosis.

Perform digestive function- digest food particles and remove dead organelles.

Primary lysosomes- these are small membrane vesicles, which have a diameter of about one hundred nm, filled with a homogeneous finely dispersed content, which is a set of hydrolytic enzymes. There are about forty enzymes in lysosomes.

Secondary lysosomes are formed by the fusion of primary lysosomes with endocytic or pinocytic vacuoles. In other words, secondary lysosomes are intracellular digestive vacuoles, the enzymes of which are supplied by the primary lysosomes, and the material for digestion is supplied by the endocytic (pinocytic) vacuole.

19. Eps, its varieties, role in the processes of synthesis of substances.

Endoplasmic reticulum in different cells it can be presented in the form of flattened cisterns, tubules or separate vesicles. The wall of these formations consists of a bilipid membrane and some proteins included in it and delimits the internal environment of the endoplasmic reticulum from the hyaloplasm.

There are two types of endoplasmic reticulum:

grainy (granular or rough);

non-grained or smooth.

The outer surface of the membranes of the granular endoplasmic reticulum contains attached ribosomes. In the cytoplasm, there can be both types of the endoplasmic reticulum, but usually one form predominates, which determines the functional specificity of the cell. It should be remembered that these two varieties are not independent forms of the endoplasmic reticulum, since it is possible to trace the transition of the granular endoplasmic reticulum to the smooth one and vice versa.

Functions of the granular endoplasmic reticulum:

synthesis of proteins intended for removal from the cell ("for export");

separation (segregation) of the synthesized product from the hyaloplasm;

condensation and modification of the synthesized protein;

transport of synthesized products to the tanks of the lamellar complex or directly from the cell;

synthesis of bilipid membranes.

The smooth endoplasmic reticulum is represented by cisterns, wider canals and individual vesicles, on the outer surface of which there are no ribosomes.

Functions of the smooth endoplasmic reticulum:

participation in the synthesis of glycogen;

synthesis of lipids;

detoxification function - neutralization of toxic substances by combining them with other substances.

The lamellar Golgi complex (mesh apparatus) is represented by an accumulation of flattened cisterns and small vesicles bounded by a bilipid membrane. The lamellar complex is subdivided into subunits - dictyosomes. Each dictyosome is a stack of flattened cisterns, along the periphery of which small vesicles are localized. At the same time, in each flattened cistern, the peripheral part is somewhat widened, and the central one is narrowed.