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The importance of cell membranes.

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The Importance Of Cell Membranes Membranes are essential to the proper functions of cells and are therefore important to living organisms. They are important because they have many tasks to complete to keep a cell working effectively. Membranes separate the living portion of the cell from the extra cellular material around and outside the cell, they are also the structure which allows of forbids certain materials from entering and exiting the cell and individual organelles. The membrane also keeps all of the organelles inside of the cell and all the parts of the organelles inside of the organelles. Membranes are made of phospholipids and proteins, as well as some carbohydrates. ...read more.


Membrane Transport of Small Molecules Because of the hydrophobic interior of the lipid bilayer, polar molecules cannot enter the cell. However, cells devised means of transferring small polar molecules. Transport proteins, each specialized for a certain molecule, can transport polar molecules across the membrane. There are several types of membrane transport proteins. Uniports simply move solutes from one side to another. Cotransport systems work by simultaneously sending two solutes across the lipid bilayer. There are two types of cotransport systems - symport, in which the solutes are sent in the same direction, or antiport, in which they are sent in opposite directions. These transport proteins work passively, meaning that the cell doesn't use energy sending the solute in or out. ...read more.


The sodium-potassium-ATPase, which uses the energy of ATP hydrolysis, pumps sodium out and potassium in, which creates a high concentration of potassium inside the cell, and a low concentration outside. The reverse applies to the sodium. Endocytosis and Exocytosis: Parts of the cell surface membrane fold into bags called vesicles, these vesicles are able to move through cell cytoplasm and join onto other membranes in the cell. When a vesicle is used to carry substances into a membrane it is called endocytosis. There are two types of endocytosis: pinocytosis- where soluble substances enter the membrane, and phagocytosis-where insoluble substances enter the membrane. When vesicles are used to remove useful substances that the cell has created a process called exocytosis is used. During this process a vesicle joins to the surface membrane and its contents leaves the cell the diagram below illustrates both processes. ...read more.

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