My first video review
The Fluid-Mosaic Model
As we learn about cells, we came across cell membranes and the fluid-mosaic model would give a description of the cell membrane. The fluid part refers to the phospholipids of a cell membrane, which, like liquid, flow. The mosaic part refers to proteins embedded in the phospholipid bilayer that act as conduits through which molecules enter and exit the cell. It is a model because its only a theory. there has been other models before. The plasma membrane is described to be fluid because of its hydrophobic integral components such as lipids and membrane proteins that move laterally or sideways throughout the membrane. That means the membrane is not solid, but more like a ‘fluid’. The membrane is depicted as mosaic because like a mosaic that is made up of many different parts the plasma membrane is composed of different kinds of macromolecules, such as integral proteins, peripheral proteins, glycoproteins, phospholipids, glycolipids, and in some cases cholesterol, lipoproteins. According to the model, the plasma membrane is a lipid bilayer (interspersed with proteins). It is so because of its phospholipid component that can fold in itself creating a double layer – or bilayer – when placed in a polar surrounding, like water. This structural feature of the membrane is essential to its functions, such as cellular transport and cell recognition. The cell membrane is made up of a variety of molecules including phospholipids, proteins, sugars, and other various building blocks. Fluid mosaic refers to the ability of these elements to shift about the cell membrane, which is ever-changing. Much of the ability to shift comes from the unsaturated lipid chains in the cell membrane, which have kinked structures that prevent the phospholipids of which they are a part from packing tightly together. The fluidity of the membrane is essential for some small molecule transfer between the inside and outside of a cell, as well as the activation of some important pathways which require molecules embedded within the cell membrane to either split or join. The plasma membrane is composed of a phospholipid by-layer. That is, you have two phospholipids, which look like…jellyfish, as in they have a head and tails, these tails are hydrophobic, they don’t like water, so they join together on the inside of the by layer, the heads are hydrophillic, so are on the outside, facing the liquid of the cell. So in the end it looks a bit like a zip, with tails in the middle, and heads on the outside. The individual lipds are not joined to each other, to things can “float” about in the layer, mainly proteins used for active transport. Active transport, is going against the concentration gradient, sorta the opposite of diffusion. This uses the intrinsic proteins (the proteins that go all the way through the membrane) This works like a very selective gate, if a molecule lands on it, and it wants it in/out the cell, the protein will open at the end with the molecule, so the molecule enters the protein, the protein closes and opens the other side, letting the molecule out. Passive transport is along the concentration gradient, so any molecules that have a lower concentration on one side of the membrane can easily pass through without the use of proteins. This is things such as diffusion.There is a phospholipid bilayer which is made up phospholips whose heads are hydrophillic and their tails hydrophobic. The heads are exposed to water, and the tails are faced inwards shielding the hydrophobie parts from water.There are receptor proteins-in this proteins, shape dictates which molecule bind extracellular matrix is a mesh of insoluble proteins with glycoproteins. The funcion is to fill space for support, made up of collagen, elastin,fibronectin, laminin and proteoglycans. Glycoprotein is a protein covalently attached to a carbohydrate. Protein filament works as a cytoskeleton. A cytoskeleton is a network of interconnected filaments, which also allows for support.Fibronectins bind to receptor proteins called integrins that are built in the plasma membrane, these help will cell communication.Transport proteins function is to allow free flow of ions through the membrane. Cholesterol gas fysed rubgsm can be found in the phospholipid bilayer proteoglycan molecuels form complexes by noncovalently attaching to long polysaccaride molecules cell recognition proteins distinguish one cell from another. some glycoproteins (proteins with short cahins of sugars) serve as identification tags that are specifically recognized by other cells cytoplasm allows for the movement of materials in cell perpheral proteins are not embedded in the lipid bilayer, they are loosely bound to the surface of the membrane integral proteins pentrate the hydrophobic core of the lipid bilayer (consists of one or more amino acids that are nonpolar).
The video depicted an excellent flow of the model and it is for that reason in which i choose to review it. Apart from leaning about cells in biochemistry,this video taught me how these membranes of cells worked and the importance of each component. I think any biochemistry student should have a clear and concise understanding of the Fluid-Mosaic Model in order to appreciate each level of science. The video however left out certain components of the model and i felt it necessary to include these aspects with a supplement description in order to fully grasp the topic of the Model.
“Cell Membranes,” YouTube Video, 11:04, posted by “Paul Andersen,” July 8, 2011,http://www.youtube.com/watch?v=y31DlJ6uGgE