Golgi Apparatus

Golgi apparatus

An organelle, named after the Italian histologist Camillo Golgi, found in all eukaryotic cells but absent from prokaryotes such as bacteria. It consists of flattened membrane-bounded compartments known as cisternae. In most cells, the Golgi cisternae are organized into stacks. Different cell types contain from one to several thousand Golgi stacks. The Golgi apparatus sorts newly synthesized proteins for delivery to various destinations, and modifies the oligosaccharide chains found on glycoproteins and glycolipids. See Cell organization

The Golgi apparatus acts at an intermediate stage in the secretory pathway. A subset of the proteins synthesized by the cell are inserted into the endoplasmic reticulum. Most such proteins are then delivered to the Golgi apparatus by means of coat protein II (COPII) transport vesicles, which form at endoplasmic reticulum exit sites. Newly synthesized proteins traverse the Golgi stack until they reach the trans-most Golgi compartment, which is termed the trans-Golgi network to connote its extensive tubulation. The trans-Golgi network sorts the proteins into several types of vesicles. Clathrin-coated vesicles carry certain proteins to lysosomes. Other proteins are packaged into secretory vesicles for immediate delivery to the cell surface. Still other proteins are packaged into secretory granules, which undergo regulated secretion in response to specific signals. This sorting function of the Golgi apparatus allows the various organelles to grow while maintaining their distinct identities. See Cell membranes, Endoplasmic reticulum, Lysosome

The best understood of the processing reactions carried out by the Golgi apparatus is the remodeling of oligosaccharides (chains of six-carbon sugars) that are attached to glycoproteins. During insertion of a newly synthesized protein into the endoplasmic reticulum, one or more copies of a 14-sugar oligosaccharide may be attached to the amino acid asparagine at specific locations in the polypeptide chain. As the protein passes through the Golgi stack, the asparagine-linked oligosaccharides are modified to generate a diverse range of structures. Additional oligosaccharides may become linked to the amino acids serine and threonine. Although the particular oligosaccharide modifications are quite different in animal, plant, and fungal cells, the Golgi apparatus always functions as a “carbohydrate factory.” See Oligosaccharide

The Golgi apparatus also carries out other processing events, including the addition of sulfate groups to the amino acid tyrosine in some proteins, the cleavage of protein precursors to yield mature hormones and neurotransmitters, and the synthesis of certain membrane lipids such as sphingomyelin and glycosphingolipids. See Lipid, Protein

Golgi Apparatus

an intracellular reticular structure; the organelle associated with the synthesis of various inclusion bodies. Named for the Italian histologist C. Golgi.

The Golgi apparatus has a highly variable form; its appearance under the microscope varies from that of a complex netlike structure (a compact form occurring in vertebrates) to that of individual sinuous or rodlike bodies (a dispersed form, called a dictyosome, occurring in plants and invertebrates). Investigations with the electron microscope have shown that the Golgi apparatus comprises three elements: a system of (five to eight) flat cisternae (γ-membranes, 70–80 angstroms thick), vesicles (300–500 angstroms in diameter), and large vacuoles (0.2–0.3 microns in diameter). The Golgi apparatus is located near the nucleus or around the centrosome. On fixed material, it is revealed by impregnation with silver salts or osmic acid. The observation of living cells has confirmed the existence of the Golgi apparatus. The organelle contains lipids, lipoproteins, and phospholipids, but is relatively low in enzymes. The function of the Golgi apparatus is involved with the production of the various formed elements of the cell’s vital activities, such as secretory granules and vitelline lamellae, collagen, lipid, and glycogen inclusions, and melanosomol granules. Deposits of vital dyes, ascorbic acid, iron salts, and colloid silver are observed in the Golgi region. The activity of the Golgi apparatus is also implicated in the production of primary lysosomes. the acrosomes of spermatozoa, and the lamellae of plant cells. The role of the various components of the Golgi apparatus in these processes differs; the vesicles and cisternae are regarded as the functional parts of the Golgi apparatus, while the vacuoles only serve in the transport of substances. The dynamics of the incorporation of tagged amino acids confirm the fact that the Golgi apparatus is the final link in an intracellular “conveyor” that produces a protein secretion. The proteins synthesized on the ribosomes enter the Golgi apparatus through the cisternae of the endoplasmic reticulum, where they are concentrated and packed into granules. In the synthesis of protein products, the Golgi apparatus— the “packing plant”—forms the secretory granules. In the production of carbohydrates (mucopolysaccharides, glycoproteins), the intracellular “conveyor” in effect switches over to another product and the Golgi apparatus participates in the synthesis of polysaccharides. In mucus, bone, and cartilage cells, tagged sugar molecules are first incorporated into the Golgi apparatus and appear in other cell components only later. Sulfation, which is associated with the synthesis of acid mucopolysaccharides, also takes place in the Golgi apparatus.

REFERENCES

Rukovodstvo po tsitologii, vol. 1. Moscow-Leningrad, 1965. Pages 185–200.
Alov. I. A., A. I. Braude. and M. E. Aspiz. Osnovy funklsionainoi morfologii kletki. Moscow, 1966. Pages 82–113.

I. A. ALOV

Golgi apparatus

[′gȯl‚jē ‚ap·ə‚rad·əs] (cell nad molecular biology) A cellular organelle that is part of the cytoplasmic membrane system; it is composed of regions of stacked cisternae and it functions in secretory processes.

Golgi apparatus

apparatus

[ap″ah-rat´tus] (pl. appara´tus, apparatuses) an arrangement of a number of parts acting together to perform a special function.Golgi apparatus see golgi apparatus" >golgi apparatus.juxtaglomerular apparatus a collective term for the juxtaglomerular cells in a nephron.lacrimal apparatus see lacrimal apparatus.Wangensteen's apparatus a nasal suction apparatus connected with a duodenal tube for aspirating gas and fluid from stomach and intestine.

complex

[kom´pleks] 1. the sum, combination, or collection of various things or related factors, like or unlike; e.g., a complex of symptoms (see syndrome).2. a group of interrelated ideas, mainly unconscious, that have a common emotional tone and strongly influence a person's attitudes and behavior.3. that portion of an electrocardiographic tracing which represents the systole of an atrium or ventricle.AIDS-related complex (ARC) a complex of signs and symptoms occurring in HIV infection including fever, weight loss, prolonged diarrhea, minor opportunistic infections, lymphadenopathy, and changes in cells of the immune system.antigen-antibody complex here the complex formed by the noncovalent binding of an antibody and antigen. Complexes of antibodies belonging to certain immunoglobulin classes may activate complement. Called also immune complex.anti-inhibitor coagulant complex (AICC) a concentrated fraction from pooled human plasma, which includes various coagulation factors. It is administered intravenously as an antihemorrhagic in hemophilic patients with inhibitors to coagulation factor VIII" >coagulation factor VIII.atrial complex the P wave of the electrocardiogram, representing electrical activity of the atria. See also complex" >ventricular complex.castration complex in psychoanalytic theory, unconscious thoughts and motives stemming from fear of loss of the genitals as punishment for forbidden sexual desires.Electra complex libidinous fixation of a daughter toward her father. This term is rarely used, since oedipus complex is generally applied to both sexes.factor IX complex a sterile, freeze-dried powder consisting of partially purified coagulation factor IX fraction, as well as concentrated factor II, VII, and X fractions, of venous plasma from healthy human donors. It is used in the prophylaxis and treatment of bleeding in patients with hemophilia B, replacement of factor VII in patients deficient in that factor, and treatment of anticoagulant-induced hemorrhage. Administered intravenously.Ghon complex primary complex (def. 1).Golgi complex golgi apparatus" >golgi apparatus.HLA complex the human major histocompatibility complex, which contains the hla antigens.immune complex antigen-antibody complex.inclusion complex one in which molecules of one type are enclosed within cavities in the crystalline lattice of another substance.inferiority complex unconscious feelings of inadequacy, producing shyness or timidity or, as a compensation, exaggerated agressiveness and expression of superiority; based on Alfred Adler's concept that everyone is born with a feeling of inferiority stemming from real or imagined physical or psychological deficiency, with the manner in which the inferiority is handled determining behavior.interpolated premature ventricular complex a premature ventricular complex that does not interfere with the conduction of the next sinus beat, i.e., it lacks the usual following compensatory pause.major histocompatibility complex (MHC) the chromosomal region containing genes that control the antigens" >histocompatibility antigens; in humans it controls the hla antigens.membrane attack complex (MAC) C5b,6,7,8,9, the five-molecule complex that is the cytolytic agent of the complement system.Oedipus complex see oedipus complex.primary complex 1. the combination of a parenchymal pulmonary lesion (Ghon focus) and a corresponding lymph node focus, occurring in primary tuberculosis, usually in children. Similar lesions may also be associated with other mycobacterial infections and with fungal infections.2. the primary cutaneous lesion at the site of infection in the skin, e.g., chancre in syphilis and tuberculous chancre.QRS complex a group of waves seen on an electrocardiogram, representing ventricular depolarization. Called also QRS wave. It actually consists of three distinct waves created by the passage of the cardiac electrical impulse through the ventricles and occurs at the beginning of each ventricular contraction. In a normal surface electrocardiogram the R wave is the upward deflection; the first downward deflection represents a Q wave and the final downward deflection is the S wave. The Q and S waves may be extremely weak and sometimes are absent.
One abnormality of the QRS complex is increased voltage resulting from enlargement of heart muscle, which produces increased quantities of electric current. A low-voltage QRS complex may result from toxic conditions of the heart, most commonly from fluid in the pericardium. Pleural effusion and emphysema also can cause a decrease in the voltage of the QRS complex.VATER complex an association of congenital anomalies consisting of vertebral defects, imperforate anus, tracheoesophageal fistula, and radial and renal dysplasia.ventricular complex the Q, R, S, and T waves of the electrocardiogram, representing ventricular electrical activity. See also complex" >atrial complex.

Gol·gi ap·pa·ra·tus

(gol'jē), a membranous system of cisternae and vesicles located between the nucleus and the secretory pole or surface of a cell; concerned with the investment and intracellular transport of membrane-bounded secretory proteins, and the synthesis of polysaccharides and glycoproteins. Synonym(s): dictyosome, Golgi body, Golgi complex, Golgi internal reticulum, Holmgrén-Golgi canals

Golgi apparatus

n. A network of stacked membranous vesicles, present in most living cells, that stores and modifies proteins and other macromolecules and transports them within the cell or excretes them from the cell. Also called Golgi body, Golgi complex.

Gol·gi ap·pa·ra·tus

(gol'jē ap'ă-rat'ŭs) A membranous system of cisterns and vesicles located between the nucleus and the secretory pole or surface of a cell; concerned with the investment and intracellular transport of membrane-bounded secretory proteins.

Golgi apparatus

A collection of stacked, flattened, cup-shaped sacs situated in the CYTOPLASM of cells near the nucleus and concerned with the movement of materials within the cell. The Golgi apparatus receives protein-containing vesicles from the endoplasmic reticulum, glycosylates them, sorts them into groups for different locations and transports them to other parts of the cell or to the cell membrane for export. (Camillo Golgi, 1843–1926, Italian microscopic anatomist).

Fig. 178 Golgi apparatus . The secretory vesicles carry products from the apparatus to the edge of the cell where they may be released.

Golgi apparatus

dictyosome

a series of cell ORGANELLES consisting of a stack of membrane-lined vesicles called CISTERNAE, first described by Camillo Golgi in 1898 but only clearly defined from studies with the ELECTRON MICROSCOPE. See Fig. 178 . The membranes of the Golgi apparatus are produced from vesicles pinched off from the ENDOPLASMIC RETICULUM and secretory vesicles are formed by the apparatus which move to the periphery of the cell and may carry out EXOCYTOSIS. The apparatus is thought to have a storage role as well as enabling the assembly of simple molecules into more complex ones, for example, the packaging of carbohydrates and proteins into glycoprotein.

Golgi,

Camillo, Italian histologist and Nobel laureate, 1844-1926. Golgi apparatus - a membranous system of cisternae and vesicles concerned with intracellular transport of membrane-bounded secretory proteins. Synonym(s): dictyosome; Golgi body; Golgi complex; Golgi internal reticulum; Holmgrén-Golgi canalsGolgi body - Synonym(s): Golgi apparatusGolgi cellsGolgi complex - Synonym(s): Golgi apparatusGolgi corpuscleGolgi internal reticulum - Synonym(s): Golgi apparatusGolgi osmiobichromate fixative - an osmic-bichromate mixture used to demonstrate nerve cells and their processes.Golgi stain - any of several methods for staining nerve cells, nerve fibers, and neuroglia.Golgi tendon organ - a proprioceptive sensory nerve ending embedded among the fibers of a tendon. Synonym(s): neurotendinous organ; neurotendinous spindleGolgi zone - part of the cytoplasm occupied by the Golgi apparatus.Golgi-Mazzoni corpuscle - an encapsulated sensory nerve ending.Holmgrén-Golgi canals - Synonym(s): Golgi apparatus

Gol·gi ap·pa·ra·tus

, Golgi body , Golgi complex (gol'jē ap'ă-rat'ŭs, bodē, kompleks) A membranous system of cisterns and vesicles located between the nucleus and the secretory pole or surface of a cell.

Golgi apparatus

Golgi apparatus

Gol′gi apparat`us

Gol·gi apparatus

Golgi Apparatus

Golgi apparatus

Golgi Apparatus

REFERENCES

Golgi apparatus

Golgi apparatus

apparatus

complex

Gol·gi ap·pa·ra·tus

Golgi apparatus

Gol·gi ap·pa·ra·tus

Golgi apparatus

Golgi apparatus

dictyosome

Golgi,

Gol·gi ap·pa·ra·tus

Golgi apparatus

Synonyms for Golgi apparatus

noun a netlike structure in the cytoplasm of animal cells (especially in those cells that produce secretions)

Synonyms

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