Fluid Mosaic Model

Only available on StudyMode
  • Download(s) : 283
  • Published : July 2, 2012
Open Document
Text Preview
here's a short preview of this essay with formatting removed for you to read Have a little read: ... The cell membrane structure-Fluid mosaic model The cell membrane separates a watery cytoplasm from a watery external environment also known as ECF. The phospholipids are arranged in a double layer (lipid layer) with the hydrophilic heads facing outward (cytoplasm or ECF) and the hydrophilic tails turned in towards each other. The unsaturated fatty acids are not bonded to each other and form a fluid. Fluid Mosaic model. The term "fluid" is used because the phospholipid molecules and proteins that make up the membrane are free to drift around in fluid motion. The term "mosaic" is used to describe the position of the protein molecules. The molecules are placed randomly and there is no set pattern. Embedded within the lipid bilayer are different proteins (hydrophobic parts interact with the hydrophobic tails of the phospholipids). The hydrophilic parts of the proteins protrude either in to the cytoplasm or into the ECF. Some of the proteins are anchored in place while other proteins move about within the bilayer. Various organelles within the cytoplasm are also bounded by membranes similar in structure to the cell membrane except for specific combinations of lipids and proteins depending on the particular functions of the organelle. Some of the proteins extending into the ECF have carbohydrates attached (glycoprotein) The cell membrane has various functions. One of the most important is to isolate the cytoplasm from the external environment. In order to do this, the cells must be able to retain precious nutrients and eliminate wastes. Also, substances that are fat soluble (e.g. vitamins A, D and E) pass through easily but they are rare in the cell's environment because they are not water soluble. Substances which are water soluble such as salts, amino acids and sugars, cannot dissolve in lipids and so cannot pass through the bilayer. A second important function of the...
tracking img