Golgi Apparatus: Definition, Structure & Functions

Ans. The Golgi complex secretes pectic chemicals from the intermediate lamella and different polysaccharides from the cell wall. Secretion vesicles transport them to the site of new wall formation.

Ans. They are cisternae that have enlarged and become modified to produce vacuoles. The developing or concave face produces the vacuoles. 

• Amorphous or granular material is found in Golgian vacuoles. 
• Lysosomes are seen in several of the Golgi vacuoles.

Ans. The Golgi apparatus, also known as the Golgi complex or Golgi body, is a membrane-bound organelle found in eukaryotic cells (those with clearly defined nuclei) that consists of a series of flattened, stacked pouches known as cisternae. 

• The Golgi apparatus is in charge of transporting, altering, and packaging proteins and lipids into vesicles so that they can be delivered to specific locations.
• It is found in the cytoplasm, close to the cell nucleus and next to the endoplasmic reticulum. 
• Much of the cell wall material also goes through the Golgi in plant cells.

Ans. Between the "cis" face and the "trans" face, the Golgi apparatus is structurally polarised, with three major compartments. These faces are biochemically separate, with each section having a distinct enzymatic composition. 

• The membranes on the cis face are usually thinner than the others.
• The Golgi apparatus is made up of four to eight cisternae in most species, but it can be as many as 60 cisternae in some single-celled organisms. 
• The cisternae are held together by matrix proteins, while cytoplasmic microtubules sustain the entire Golgi apparatus. 
• "Cis" (cisternae closest to the endoplasmic reticulum), "medial" (central layers of cisternae), and "trans" (cisternae farthest from the endoplasmic reticulum) are the three basic compartments of the apparatus (cisternae farthest from the endoplasmic reticulum). 
• The cis Golgi network and the trans Golgi network, which are made up of the outermost cisternae at the cis and trans faces, respectively.
• They are in charge of sorting proteins and lipids that the organelle receives (at the cis face) or releases (at the trans face).

Ans. The Golgi complex or apparatus in animal cells is either single or consists of a single connected complex. Localised (most vertebrate cells) and diffused (most vertebrate cells) are the two conditions (most invertebrate cells, liver and nerve cells of vertebrates).

• The compacted organelle is localised. It usually happens on one end of the cell, between the nucleus and the periphery. 
• For example, the dispersed organelle forms a network around the nucleus in nerve cells.
• The Golgi apparatus in plant cells is made up of dictyosomes, which are disconnected units. 
• Their numbers range from one in certain basic algae to 25000 in Chara's rhizoidal cell. 
• Each plant cell typically contains 10-20 dictyosomes. Golgi Somes are Golgi apparatus units that can be found in up to 50 units per liver cell.

Ans. The Golgi complex is made up of a stack of membrane-bound saccules or cisternae that are usually 4-8 (range 3-20). The saccules or cisternae membranes are smooth but vary in thickness, and they enclose a 60-90 lumen. 

• Lumen is made up of a fluid substance called a matrix. The adjacent cisternae in a stack are separated by a space of 100-300 A. 
• A thin layer of cytoplasm with parallel fibrils covers the intercisternal region.
• The saccules are usually bent to give the Golgi apparatus a distinct polarity. The equipment has a convex on one side and a concave on the other. 
• The convex side of the apparatus is known as the forming (=formative, cis-face) face, whereas the concave side is known as the maturing face (trans-face). 
• The maturing facial membranes are around 7-8 nm thick, while the developing face membranes are about 4 nm thick.
• The endoplasmic reticulum delivers (transitional) vesicles to the developing face. 
• Coated vesicles and intercisternal connectives help their contents flow through diverse cisternae. 

Ans. Here are some of the functions:

• Secretion: All glandular cells rely upon the Golgi apparatus to concentrate and pack their products in a soluble protein coat. Exocytosis or reverse pinocytosis is how they get out of the cells.
• Transformation of membranes: The Golgi complex causes membrane transfor­mation, or the transformation of one type of membrane (for example, the ER membrane) into another (e.g., selectively permeable plasma membrane, a differentiated membrane of lysosome). The complex is also involved in plasma membrane recycling.
• Glycolipids and glycoproteins: Proteins produced by the rough endoplasmic reticulum and lipids produced by the smooth endoplasmic reticulum both reach the Golgi apparatus' cisternae. Glycoproteins and glycolipids are formed when they mix with carbohydrates.
• Simple carbohydrates: The Golgi complex produces sialic acid and galactose.
• Complex carbohydrates: Pectic compounds, mucopolysaccharides, hyaluronic acid, chondroitin sulphate, hemicelluloses, and other complex carbohydrates are generated inside the Golgi complex, in addition to glycogen and starch.

Ans. The main components of the structure of the Golgi Apparatus are as follows:

• Cisternae
• Lumen
• Transport Vesicle
• Trans Face
• Outgoing Transport Vesicle

Ans. The differences between the Golgi Cisternae and ER Cisternae are as follows:

Ans. Golgi apparatus or complex is a membrane-bound organelle. Its structure is similar to that of endoplasmic reticulum and lysosomes. It has a single lipid bilayer membrane as opposed to the double lipid bilayered membranes. The Golgi complex is part of the GERL system, which stands for the Golgi Apparatus, the Endoplasmic Reticulum and the Lysosomes.

Ans. (A) Exocytotic Vesicles: Exocytotic vesicles consist of proteins that are used for extracellular release. After packaging is complete, the vesicles move towards the plasma membrane, where they fuse and release the required proteins.

(B) Secretory Vesicles: Secretory Vesicles are also known as Regulated secretion, which is also made up of proteins. After packaging is complete, the vesicles are released until a signal is received.

(C) Lysosomal Vesicles: This category of vesicles is made of proteins and ribosomes. In this vesicle first fuses with the late endosome and is later transferred to the lysosome.

Ans. The Endoplasmic Reticulum is responsible for the transportation of eukaryotic cells and is used for the folding of proteins. It is divided into rough endoplasmic reticulum and smooth endoplasmic reticulum. The proteins transported by the endoplasmic reticulum are marked with an address tag called signal sequence. The majority of proteins are retained in the motif.

Ans. A vesicle is a structure found inside and outside the cell which is enclosed by a lipid bilayer. It is formed during the process of secretion and uptake. Vesicles act as a transport material within the plasma membrane. The process of secretion that takes place inside the body is called exocytosis. Vesicles perform a variety of functions, including temporary storage of food, and buoyancy control and also work as chemical reaction chambers.