Hello everybody and welcome to another re of mine. Today we are going to focus on cell membrane or plasma membrane or otocolis liquid barrier or sometimes they are called as a plasma lemma. One of the important parts of the cell, so let's start. What is a cell membrane or plasma membrane? Why is it so important? Let's have a look. The most important factor is that it separates inside of the cell from the outside environment. They act as a wall. The bilayer, they are like butter, laving, only select few cargos to go inside and throw things out. Just as you see at any airports where the password control wouldn't let you in if you don't have proper documents or if you are carrying some fake documents, they will kick you out. Just like that, plasma membrane proteins, they act as a password control officers and they would let bad things that go in and they will throw out bad things from inside the cell to the outside. As I said, they transport nutrients inside the cell and expel waste from the cell. Very, very important thing. There are different types of cell membranes, but for our understanding here we are just going to focus on general model. Structure of plasma membranes is very interesting. It's very simple yet, very complicated, quite interesting. Plasma membrane is made up of both lipids and proteins as well as cholesterol moities. Largely it consists of phospholipid bilayer, but proteins play a crucial role in the cargo transportation and cell signaling pathways. The outer layer is made up of phosphor, cadial, coolean, spingamilin or spingamilin. I will use pronounced that and glycolipids. The inner part is composed of phosphatidial ethyl amine, phosphatidial serine and phosphatidial inocetol. Cholesterol is present on both sides. So right here, so this is cytosol and this is the outside of the cell and this is like a wall. A strong wall. Right, so let's see the membrane protein. Now plasma membrane is made up of both lipids and proteins as well as cholesterol moities. Although as I mentioned before, lipids form the fundamental part of this lipid bilayer. Protein carry out membrane functions. Most of the plasma membrane is composed of 50% protein and 50% lipid by weight. Carbohydrate portion is composed of about 5 to 10%. Two scientists, Jonathan Singer and Garth Nicholson proposed the fluid mosaic model of plasma membrane in 1972. It is now accepted as a basic model of all biological membrane. So what is about fluid mosaic model? So according to this model, there are integral membrane proteins, it's very full of proteins. Integral proteins, as the name suggests, are embedded inside the membrane and very full of proteins, are indirectly bound to the membrane by protein, protein interactions. Integral proteins are transmembrane proteins with portion exposed on both sides of the membrane and portion of the protein outside the membrane is glycosylated. So glycosylation is a process where carbohydrate moities are attached to the hydroxyl group for another molecule as you're right here. This is glycosylation, right in the blue. Right. Now let's have a look at this phospholipid molecule a little bit in detail. It's a very interesting molecule because it's both hydrophilic as well as hydrophobic, which means it loves and hates water at the same time. It's also called an amphiphilic molecule. It's a love and hate story with water. Phospholipid molecule has hydrophilic head and two hydrophobic tails. On the hydrophobic head, as you see here, the top phosphate group is attached to glycerol molecule, whereas hydrophobic tails have saturated and unsaturated fatty acid chain right here. So this is phosphate group, attached to glycerol molecule and these two tails have saturated and unsaturated fatty acid, usually. Right. Let's have a look at the proteins now. Again, there are integral proteins and there are completely inside the membrane, as you see right here, they are inside the membrane, embedded inside the membrane, interacting with the hydrophobic region of the phospholipids. Whereas some proteins are composed of multiple segments of single proteins and are extensively folded, as you can see right here, this number two and number three. Although number two is not so extensively folded, however, you see number three is really folded. It's called a beta sheet and it's it's band the membranes. This is alpha helix number one, number two. This is better sheet. So it's very complicated inside and this these proteins actually, you know, are very important in cell signaling pathways as well as cargo transportation from inside and outside the cell. So they are like our password control officers who wouldn't allow everybody to just get in and get out without without checking. So a very important part of this cell membrane. Now, let's have a look at the disease in plasma membrane. If there is any problem with the plasma membrane, its integrity is just if its integrity is disturbed, it can cause severe consequences. Membrane is composed of arrays of lipids and proteins as you've just seen and any damage to its integrity could lead to severe consequences. There are many diseases associated with disturbance in the membrane integrity for instance, the presence of high level of cholesterol in blood, some forms of diabetes and obesity as well as graves disease, graves disease disease of immune system, where that results in over production of thyroid hormones or so-called as hyperthyroidism. Also cell structure, instability, causes, erythrocytes abnormalities and altered transport system. Mostly in lungs, but I'm sorry, abnormalities and altered transport system, the cystic fibrosis, a genetic disorder that affects mostly the lungs, but also it affects pancreas, liver, kidneys, and intestine caused by mutation in genes called cystic fibrosis transmembrane conductance regulator or CFTR. So there are many diseases associated with it, so it's very, very crucial that the integrity of plasma membrane needs to be maintained and our cell phone does a good job at it. Alright, so this is the end of the plasma membrane presentation, a very small presentation. If you have any questions, please write to me and I'll be very, very happy to answer your questions. Also, the next presentation is going to be about cytoskeleton, so thank you so much for your time. If you've come all the way here and I'm very glad that you've come all the way here and if you like it, please subscribe to the channel for more cell and molecular biology, education and stuff and presentation information. Alright, have a good day, I'll see you later, Tata, take care, bye-bye.