The Structure of Plasma Membrane

The plasma membrane is also known as cytoplasmic membrane; its primary function is to offer protection to the cell from surrounding environment. The plasma membrane consists of a phospholipids bilayer which also encompasses protein thereby allowing specific organic molecules and ions into the cell. The structure of plasma membrane is demonstrated as fluid mosaic model and is 7-10 nm thin (Marieb, Elain, and Katja p. 84). It is made up of the following components; proteins, carbohydrates, cholesterol, and phospholipids. The carbohydrates exist on the outer surface of the cells, and either interacts with the lipids (forming glycolipids) or with the proteins (resulting in the formation of glycoproteins). The phospholipids are located in the central framework of the plasma membrane, are amphipathic, and consist of hydrophobic tail and polar head group. Cholesterol prevents rigidity of the membrane and ensures only particular molecules and ions enter into the cell. Proteins are located in the phospholipid bilayer controls movement of molecules and ions into the cell. The proteins also respond to receptors found in other cells and the surrounding environment.

The plasma membrane has a phospholipids bilayer structure that helps in control of the movement of substances in and out of the cell. The selective permeability of the plasma is fostered by its structure which consists of tightly packed phospholipids and also the hydrophobic interior, thereby allowing specific substances such alcohol, oxygen, and carbon dioxide gases into the cell. Molecules move across the cell through diffusion. The rate of diffusion in to the cell is dependent on its solubility and size. Oxygen and carbon dioxide are non-polar molecules that dissolve easily in the cell membrane due to their small size (Vacha, Berkowitz, & Jungwirth, p. 4498). The membrane potential influences the movement of potassium and sodium ions into the cell where the barrier of the cell membrane separates the negative and positive charge. Usually, the cell has a high negative charge as compared to the outside environment. The voltage across the membrane and lower sodium ions concentration outside the cell facilitates the movement of sodium ions in and out of the cell. Thus sodium ions move into the cell through gradient concentration through the presence of significant concentration of excess of potassium (Korn p. 257).

Works Cited

Korn., Edward D. Structure and Function of the Cell Membrane. Journal of General Physiology;

2013 Jul 1; Vol. 52 No. 1: 257–278.

Marieb, Elaine N., and Katja N. Hoehn. Human Anatomy & Physiology, Global Edition, Pearson

Education Limited, 2014. 1-134 ProQuest Ebook Central,

http://ebookcentral.proquest.com/lib/wsudt/detail.action?docID=4742034. Created from wsudt on 2018-03-29 05:58:11.

Vacha., Robert., Berkowitz, Max. L & Jungwirth Pavel. Molecular Model of a Cell Plasma

Membrane With an Asymmetric Multicomponent Composition: Water Permeation and Ion Effects. Biophysical Journal, 2011 vol. 3; no. 96(11): 4493–4501.