Cell Membrane Structure!!!

This is a picture of a cell membrane. 
  

In class, we have been studying about the structure of the cell membrane. The cell membrane is a fluid mosaic of lipids, proteins, and carbohydrates. Lipids are hydrophobic, in which the molecules consists of long 18-22 carbon. The backbones consists of a small amount of oxygen containing groups. Fats, steroids, and phospholipids are very important to the functioning of membranes in cells. Fats are categorized into two different classes of molecules, which are saturated and unsaturated. Saturated fatty acids don't have carbon-carbon double bonds. Unsaturated fatty acids have one to four double bonds between adjacent carbon atoms.

Phospholipids contain two fatty acid tails, which are hydrophobic that is attached to a glycerol head. Phospholipids are hydrophobic and hydrophilic because the tails repel water and the heads attract water. They serve as a very important function in the cells of all organisms. They form the phospholipids membranes which surrounds the cell and intracellular structures. Steroids are types of lipids that are based on a molecule with four carbon rings. It includes a lot of hormones of animals and cholesterol. In order for the cell to grow, the cell membrane must be a dynamic structure and respond to environmental changes. The correct ratio of saturated to unsaturated fatty acids keeps the membrane fluid at any temperature. 


Proteins are a different group of molecules that are composed of amino acids. They are classified into two categories, integral proteins and peripheral proteins. Integral proteins are transmembrane proteins, with hydrophobic regions that cover the surface of the membrane. They transmit signals in and out of the cell. Peripheral proteins stick to only one side of the membrane, which are usually attached to integral proteins. Proteins are much larger than lipids, and they move more slowly. Carbohydrate groups are attached to lipids, glycolipids, or proteins, or glycoproteins. These short oligosaccharides are chains f sugar molecules.The lipid bilayer is the main fabric of the membrane, and its structure creates a semi-permeable membrane. The functions in the membrane are determined by proteins. I have a good understanding of how the cell membrane functions, but I'am still confused on what certain things plays a certain role in the cell membrane.