Role of Golgi bodies and lysosomes in a Cell Structure

Organelles are cell portions that have been altered and/or specialised to conduct one or more critical functions, similar to the human body’s organs (such as the heart, lung, and kidney, with each organ performing a different function). Organelles are found in both eukaryotic and prokaryotic cells, however bacterial organelles are simpler and are not membrane-bound.

Organelles come in a variety of shapes and sizes. Some are normally solitary (such as that of the nucleus and Golgi apparatus), while others (including mitochondria, chloroplasts, peroxisomes, and lysosomes) can be many (hundreds to thousands). The gelatinous fluid that fills the cell and covers the organelles is known as the cytosol.

Structure of Golgi Apparatus

The Golgi apparatus is a collection of fused, flattened membrane-enclosed discs known as cisternae (often called “dictyosomes”) that originate from vesicular clusters that bud off the endoplasmic reticulum in most eukaryotes. A mammalian cell normally has 40 to 100 cisternae stacks. In most stacks, four to eight cisternae are present; however, some protists have as many as sixty cisternae. The cis Golgi network (CGN) and the trans Golgi network (TGN) are two primary networks made up of cisterns divided into cis, medial, and trans compartments (TGN). 

The TGN is the ultimate cisternal structure, from which proteins are packaged into vesicles bound for lysosomes, secretory vesicles, or the cell surface. The TGN is normally placed next to the stack, but it can also be placed separately. In yeast and plants, the TGN may function as an early endosome. Each cisternal stack in eukaryotes has a cis entering face and a trans exit face. The morphology and biochemistry of these faces are distinct. Individual stacks include an array of enzymes that selectively change protein cargo. These changes have an impact on the protein’s fate. The Golgi apparatus’ compartmentalization is useful for separating enzymes and maintaining sequential and selective processing steps: enzymes catalysing early modifications are found in the cis face cisternae of the Golgi stacks, while enzymes catalysing later modifications are found in the trans face cisternae. 

Role of Golgi Bodies in Cell Structure

The Golgi apparatus is a primary gathering and dispatch site for endoplasmic reticulum protein products (ER). Proteins are packed into vesicles in the ER, which then merge with the Golgi apparatus. These cargo proteins have been changed and are targeted for exocytosis or intracellular usage. The Golgi can be compared to a post office in this regard: it packages and labels objects before sending them to various regions of the cell or to the extracellular space. Lipid transport and lysosome production are also carried out by the Golgi apparatus. Individual stacks contain distinct enzyme combinations, allowing cargo proteins to be processed in stages as they move from the cisternae to the trans Golgi face. Enzymatic processes take place only near the Golgi stacks’ membrane surfaces, where enzymes are tethered. The ER, on the other hand, contains soluble proteins and enzymes within the lumen. Post-translational modification of proteins accounts for a large portion of enzymatic processing. Phosphorylation of oligosaccharides on lysosomal proteins, for example, happens early in the CGN. 

Structure of Lysosomes

Lysosomes are normally small, ranging in size from 0.1 to 0.5 m in diameter, though they can grow to 1.2 m in diameter. They are spheres composed of a lipid bilayer that encloses fluid containing a range of hydrolytic enzymes and have a simple structure. Phospholipids are lipid molecules with hydrophilic phosphate group heads, a glycerol molecule, and hydrophobic fatty acid tails that make up the bilayer. When phospholipids are introduced in a solution containing water, they eventually occur as double-layered membranes due to these variations in characteristics. To avoid water, the phosphate group heads go to the outside of the layer, whereas the fatty acid tails move to the interior. 

Many additional membranes in the cell contain phospholipids, including the cell membrane, which encompasses the entire cell, the nuclear membrane (or nuclear envelope), the Golgi apparatus, and the endoplasmic reticulum. Lysosomes are generated by the endoplasmic reticulum budding off of the Golgi apparatus, and the hydrolytic enzymes inside them are formed in the Golgi apparatus.

Functions of Lysosomes

Many complex substances, including carbohydrates, lipids, proteins, and nucleic acids, are digested by lysosomes, which the cell subsequently recycles for different use. Because their hydrolytic enzymes work best at this pH rather than the neutral pH of the rest of the cell, lysosomes have an acidic pH (about pH 5). Hydrolytic enzymes specialise in the hydrolysis of big molecules. A molecule of water is added to a chemical during hydrolysis, which causes it to cleave. The lysosome can be regarded as the “digestive system” of the cell since it uses enzymes to break down molecules, just like the digestive system of the human body does.

Lysosomes break down a wide range of substances. If an endocytic vesicle (a vesicle that delivers particles into the cell) merges with them, they can break down food molecules into smaller bits. They can also engage in autophagy, which is the elimination of organelles that aren’t working properly. Furthermore, lysosomes play a part in phagocytosis, or “cell eating,” which occurs when a cell swallows a molecule in order to break it down. For example, phagocytes consume invading bacteria in order to break them down and eliminate them, and the bacteria is contained in a vesicle with which lysosomes fuse. The bacteria is then broken down by the lysosomes.

Conclusion

Every single species on Earth, including single-celled and multicellular organisms, is made up of cells. To keep the entire system alive, the cells give shape, structure, and perform various functions. Organelles are functional structures that are found throughout the cell and are engaged in a variety of cellular processes. All these organelles within a cell, are also known as vesicles. And they serve a crucial purpose because we must compartmentalise all of the operations within the cell. As a result, a membrane must surround the machinery within a cell that produces diverse products. Organelles are hence membrane-bound. They also distinguish one function from another. The mitochondrion, for example, has the role of creating energy, whereas the lysosome has the function of breaking down large molecules into little molecules.