Structure of golgi body

Last Updated on Sat, 17 Dec 2022 | We noted in Chapter 3 that post-translational modification of polypeptides and The first steps in post-translational processing occur in the lumen of the ER. Here we find that disulphide bonds are made between cysteine residues and the first steps in glycosylation are taken. The formation of disulphide bonds is generally regarded as stabilising the three-dimensional structure of a protein, and the process of glycosylation - the adding of carbohydrate chains - is very important for many proteins - as we have noted in preceding chapters and shall note again, especially when we come to consider cell-cell recognition in neuroembryology (Chapter 19). The initial steps in glycosylation are often called core glycosylation to distinguish them from the finishing touches that are carried out later in the Golgi body (Figure 15.6). These initial steps often involve the addition of a 'core' oligosaccharide to the amide side chain of asparagine. Such glycoproteins, as we noted in Chapter 2, are consequently termed N-linked. The core oligosaccharide almost invariably consists of two units of an acetylated monosaccharide, N-acetylglucosamine (NAG), and a number of mannose and glucose units. Alternatively the carbohydrate moiety may be linked to the hydroxyl group in the side chains of serine or threonine or, more rarely, hydroxylysine and hydroxyproline. Such glycoproteins, as we noted, are consequently termed O-linked. O-linked oligosaccharides are much...

ADVERTISEMENTS: In this article we will discuss about Golgi Complex that exist in all the cells of eukaryotes:- 1. Subject-Matter of Golgi Complex 2. Structure of Golgi Complex 3. Functions. Subject-Matter of Golgi Complex: This cytoplasmic organelle is named after its discoverer Golgi. The structure was discovered in 1898. The golgi bodies are also called lipochondria. For several years there was considerable disagreement about the existence of that organelle. Most of the early biologists believed that it was an artifact of fixation or staining procedures. Studies with phase contrast microscopes in the early 1940s also indicated the existence of golgi bodies. The study of electron micrographs of thin sections of cells in 1950s finally proved beyond doubt the existence of golgi bodies in all the cells of eukaryotes (Fig. 6.1). The golgi apparatus does not exist in the prokaryotes. Structure of Golgi Complex: The electron microscopic studies have revealed that this organelle consists of series of compactly grouped smooth contoured membrane limited vesicles of variable shapes and dimensions and variable number of small vacuoles (Fig. 6.2). They are selectively stained with Neutral red stain and differ from mitochondria in staining property because they do not take Janus green stain (special stain for mitochondria). When the cytoplasm is centrifuged the mitochondria settle down first and golgi bodies afterwards. This indicates that the golgi bodies are lighter than the mitoch...

During protein synthesis, proteins meant for use within the cell are translated by free ribosomes. Proteins meant to be embedded in the cell membrane or used outside the cell are translated by ribosomes attached to the rough endoplasmic reticulum. These proteins are then transported to the Golgi body for further maturation and sorting before being released. Created by Sal Khan. In eukaryotes, free ribosome's actually assemble around the mRNA then will begin reading the code. Fairly early on a certain sequence in the RNA may be recognised which causes the whole translation process to halt while the mRNA-ribosome complex is all transferred to the endoplasmic reticulum, translation will then begin again with the growing polypeptide chain entering the ER lumen. The process is known as cotranslational localisation. Generally speaking, proteins that are destined for lysosomes, membranes or to be secreted from the cell are made on the RER. As I am sure you know, the ER (endoplasmic reticulum) is a network of cisternae around the nucleus. Thus, there is only one network of ER in a cell, but within that is a number of sacs and tubes that make up the entire ER. As for the Golgi apparatus (or body), is to is made up of multiple sections of cisternae (just like the ER, yet in a different formation), and there are often multiple complexes of Golgi to be found in a single cell, with the maximum being ~20. Chromatin is a combination of DNA and protein, and is what makes a Chromosome. It ...

Golgi Apparatus Structure • The Golgi apparatus is a major organelle in most of the eukarytoic cells. • They are membrane bound organelles, which are sac-like. They are found in the cytoplasm of plant and animal cells. • The Golgi complex is composed of stacks of membrane-bound structures, these structures are known as the cisternae. An individual stack of the cisternae is sometimes referred as dictyosome. • In a typical animal cell, there are about 40 to 100 stacks. In a stack there are about four to eight cisternae. • Each cisternae is a disc enclosed in a membrane, it possess special enzymes of the Golgi which help to modify and transport of the modified proteins to their destination. • The flat sacs of the cisternae are stacked and is bent and semicircular in shape. • Each group of stacks is membrane bound and its insides are separated from the cytoplasm of the cell. • The interaction in the Golgi membrane in responsible for the unique shape of the apparatus. • The Golgi complex is polar in nature. • The membranes of one end of the stack is different in composition and thickness to the membranes at the other end. • One end of the stack is known as the cis face, it is the 'receiving department" while the other end is the trans face and is the "shipping department". The cis face of the Golgi apparatus is closely associated with the endoplasmic reticulum. • • • Golgi Apparatus Function • The cell synthesize a huge amount of variety of macromolecules. The main function of ...