+1 862 207 3288 Plasmalemma is the surrounding layer of the cell. It is situated towards the inner side of the cell-wall in plant cell but situated towards the outermost side in the animal cell. Danielli studied the ultrastructure of Plasmalemma. On the basis of some evidences he prepared a model to understand the structure of Plasmalemma. This model is also known as “The Sandwitch Model”. There after Singer and Nicholson suggested a new model . They prepared this new model after making some corrections in the Sandwitch model. This new model suggested on the basis of modern information is known as a “Fluid-mosaic model”. The “Fluid-mosaic model” is widely accepted. According to this model, the proteins molecules are found in both the outer side as well as the inner side of a bimolecular phospholipid layer of the plasmalemma. There are two types of proteins with reference to the location of proteins in the plasmalemma. viz. (a) surface proteins and (b) internal protein. Internal proteins are sandwitched in the deeper layers between the lipid molecules. The internal proteins cannot be easily extracted by chemical methods because they are sandwitched in the deeper layer of the lipid molecules. Surface proteins can be easily extracted. With reference to the functions of the cell all these proteins are of different types. These proteins are mainly in the form of enzymes. The important functions of plasmalemma is to control the entry or exit of substance in the cell. The conduction of substance through plasmalemma takes place in three ways.
