Bioscience for Anatomy of Plasma Membrane-myassignmenthelp.com

Question: Discuss about theBioscience for Anatomy of Plasma Membrane. Answer: The plasma membrane is defined as the boundary of the cell, which separates the components of the cell from the extra-cellular components. It is made up of protein and lipid molecule that forms tough, thin, pliable and hydrophobic barrier around the cell (Luckey et al., 2014). In other words it can be said that cellular membranes or plasma membrane is composed of two layers of phospholipid molecule. This bipartite layer has hydrophilic end and hydrophobic end. The hydrophilic ends are directed towards the inner and the outer surface of the membrane whereas the hydrophobic ends are buried within the interior of the membrane (Rodwell et al., 2015). This arrangement of the plasma membrane is known as fluid mosaic model as proposed by Singer and Nicolson (Rodwell et al., 2015). According to the fluid mosaic model, the hydrocarbon chain of phospholipid bilayer forms hydrophobic core that restricts diffusion of water soluble solutes through the membrane. The polar head group of the phospholipid has hydrophilic tail that remains embedded within the membrane (Lodish et al., 2000). Transport of Oxygen across plasma membrane Gases such as oxygen (O2) and CO2 (carbon di-oxide) and other small uncharged molecules which are polar in nature (urea and ethanol) are transported through the plasma membrane via passive diffusion. These molecules can diffuse across the plasma membrane without the requirement of transport proteins. Moreover, metabolic energy is not expended due to the movement of these polar molecules occur from a domain of high concentration to a region of low concentration, down the chemical concentration gradient. From the theory of thermodynamics it can be stated that such transportation reactions are spontaneous because it has positive change in entropy (delta S) and negative change in Gibbs free energy (delta G) (Lodish et al., 2000). Transport of sodium across the plasma membrane The transport of sodium ions (Na+) takes place along with potassium ions (K+) through P-class ion pump known as Na+/K+ ATPase. In the E1 configuration of Na+/K+ ATPase have three high-affinity sodium ions binding sites along with two low affinity potassium ion binding sites at the cytosolic face. Hence three molecules of Na+ are transported across the concentration in the expense ATP breakdown. While face on the exterior surface of the plasma membrane, Na+/K+ ATPase has two high affinity K+ ion binding sites, upon releasing 3 Na+, 2K+ binds to its respective binding sites and is released inside the cell (across its concentration gradient) along with the release of the phosphate ions formed as a result of ATP to ADP conversion during Na+ ion transport (Lodish et al., 2000). Transport of Sodium ions inside the cell takes place along with glucose molecule via the help of symporter (Lodish et al., 2000). References Lodish, H., Berk, A., Zipursky, S. L., Matsudaira, P., Baltimore, D., Darnell, J. (2000). Molecular cell biology 4th edition.National Center for Biotechnology Information, Bookshelf. Luckey, M. (2014).Membrane structural biology: with biochemical and biophysical foundations. Cambridge University Press. Rodwell, V., Bender, D., Botham, K. M., Kennelly, P. J., Weil, P. A. (2015).Harpers Illustrated Biochemistry 30th Edition. McGraw Hill Professional.