Vesículas (Lisossomas, Peroxissomas, Vacúolo e Glioxissomos)

#Biology #Cytology #Vesicles Lesson aimed at high school and ENEM students about cytoplasmic vesicles. Script below. Due to lack of space, it's not possible to include the video's bibliography. If you'd like, please contact me and I'll send it. Video Script: In your cell, almost all material transported here and there isn't loose, but rather through small sacs that move through the cytoplasm. One of the main roles of these sacs is transport, but some have special characteristics, such as enzymes inside them, so in addition to transport, they also digest. But let's take a step back and understand more about what this is. These sacs are called vesicles; they are essentially small balls made of a membrane with a phospholipid bilayer that can originate from various parts of the cell, but the best-known come from either the plasma membrane, the ER, or the CG. They can be separated into groups depending on their function, so let's talk about some of them: Starting with transport vesicles: as the name suggests, they transport substances from one part of the cell to another, such as the vesicles that go from the RER to the CG. Next, we have secretory vesicles, which are those that will pick up a cellular product and transport it out of the cell, such as hormones, neurotransmitters, and others. They are further subdivided depending on the cell we're talking about, such as nerve cells having synaptic vesicles to aid in synapsis; endocrine tissue cells have endocrine vesicles for hormone release; bones and cartilage have calcium-mining vesicles, and so on, each with its own vesicle. We also have vesicles with other functions, such as gas vesicles, endosomes, and several others that may be present in cells. But since this is a short class, we'll focus on three special vesicles from now on. Starting with one of the most famous, the lysosome. This vesicle is so important that it has been given the status of an organelle by several authors, and indeed it is very important. It was discovered in a study of liver cells in 1949. In this study, researchers (Christian de Duve) tested a specific enzyme that reacted to insulin. After several days of testing, they realized that the enzyme was surrounded by a membrane, like a sac, or as we mentioned before, like a vesicle. However, it was only given the name lysosome in 1955 because other digestive functions of this strange vesicle were discovered. Later, the same researcher who discovered the lysosome in 1949 received the Nobel Prize in 1974 for his discovery. But what is the importance of this organelle? Well... Lysosomes are vesicles formed in the GC that take enzymes from the RER to digest macromolecules in the cells, such as proteins, polysaccharides, lipids, and others. It works more or less like this: The RER sends specific enzymes to the GC, where these enzymes are placed inside special vesicles called late endosomes (made by endocytosis) (TUMB CLASS INTRA/EXTRA TRANSPORT). The combination of these late endosomes with these enzymes makes the enzymes mature with the addition of some chemical components, increasing the enzyme's potency. Once at maximum potency, the lysosome is ready. Then it detaches from the GC and goes to work. One of the most important things is that its membrane composition is specifically made to hold the action of these enzymes inside this sac, protecting the rest of the cell from self-decomposition. In addition to this characteristic, lysosomes can associate with other vesicles from intracellular transport, such as pinosomes and phagosomes, aiding in the digestion of almost everything that enters the cell. Finally, another function is their relationship with autophagy. This process occurs when a cell is no longer able to obtain nutrients to maintain regular processes, or has a defect that prevents its regular function. In both cases, the cell understands that it is better to destroy itself and recycle its material so that other cells can use it and survive. This function is very important for the cell, and lysosomes perform it. Animal cells have lysosomes in large numbers, but plant cells have a slightly different lysosome, and we'll talk about them now: the famous vacuoles. In essence, vacuoles are lysosomes 2.0; they do everything that animal lysosomes do, but they also have a few additional capabilities. The first is their ability to store substances, as long as they are related to the cells' digestion and excretion. Another important fact is that they are very large organelles; in fact, they occupy the largest space in a plant cell. This is a good thing, as another function of these organs is to regulate the osmotic pressure of plant cells, as we discussed in the Osmosis in Plant Cells (TUMB) class.