STRUCTURE OF THE CELL MEMBRANE

Structure of the Cell Membrane

Structure of the Cell Membrane

Introduction

The main purpose of this paper is to discuss the structure of the cell membrane and its functions in the cell transportation in the eukaryotic cell. In real cell, membrane phospholipids have a lipid bi-layer and form a three-dimensional spatial sphere that surrounds it. It has its representation usually in two dimensions.

Discussion

To carry out the chemical reactions necessary for the maintenance of life, the cell needs to maintain appropriate internal half. This is possible because the cells get separated from the outside world by a limiting membrane, the plasma membrane (Kholodenko, 2000, p. 173). Furthermore, the presence of inner membranes in eukaryotic cells provides additional compartments that limit unique environments in which to carry out highly functions necessary for cell survival.

The plasma membrane is responsible for:

selectively isolate cell content of the external environment

regular exchange of substances between the inside and outside the cell (which enters and exits the cell);

intercellular communication

Most cells have internal membranes, in addition to the plasma membrane, form and delimit compartments where they carry out the biochemical activities of the cell. The remaining selective membranes are also barriers to the passage of substances.

The plasma membrane has a thickness no greater than 5 nm (Harrison, 2000, p. 89). Because most proteins have a diameter greater than 10 nm, a major problem in understanding the basic structure of the membranes was to determine how the molecules have their arrangement in such a small space. The current model of the structure of the plasma membrane is the result of a long process that begins with indirect observations determined that the soluble compounds easily pass this barrier leading to Overton, and in 1902, to argue that its composition corresponded to a thin lipid layer, and subsequently added to this proposal, claiming that the protein composition also involved (Garrett, 2002, p. 23). Danielli and Davson in 1935 synthesized the knowledge suggesting that the plasma membrane has formed by a "lipid bilayer" with proteins attached to both sides of the same.

The integration of the chemical, physical, chemical and various microscopy techniques led to the current model of " S.J. Singer, and Nicolson, G.L. (1972) Science, 175:120 "(Singer SJ, and Nicolson, GL (1972) Science, 175:120). According to the fluid mosaic model, which has widely acceptance, the membranes consist of a lipid bi-layer (double layer of lipids) in which they have embedded various proteins.

The lipid bi-layer has got establishment as the universal basis for cell membrane structure. It is easy to observe in an electron micrograph but require specialized techniques such as X-ray diffraction and freeze-fracture techniques to reveal the details of your organization (Heck, 2001, p. 276).

The membrane is a quasi-fluid structure; it can perform its components translational movements within it. This fluidity means that most components have their links by non-covalent bonds (Adam, 1968, p. 198). Electron microscopy showed the plasma membrane as a structure of three layers, two external and dense, and clear in the ...