![]() Overall this means at low temperatures, when rate of movement is lowest, a fluid phase is maintained.Īt high temperatures, cholesterol helps to stop the formation of crystalline structures and the rigid planar steroid ring prevents intrachain vibration and therefore making the membrane less fluid. Cholesterol is important in the membrane as it helps to maintain cell membrane stability and fluidity at varying temperatures.Ĭholesterol is bound to neighbouring phospholipid molecules via hydrogen bonds and therefore at low temperatures, reduces their packing. CholesterolĬholesterol is vital for many functions in a cell, including very importantly, a major constituent of the cell membrane.Ĭholesterol itself consists of a polar head, a planar steroid ring and a non-polar hydrocarbon tail. In the bilayer, there are van der Waal forces between the fatty acid tails of the phospholipid, with electrostatic and hydrogen bonds between the hydrophilic groups and water.įig 2 – Diagram showing the structure of both the phospholipid bilayer and an individual phospholipid. They spontaneously form bilayers in the water with the head groups facing out and the tail groups facing in. Phospholipid molecules are therefore amphipathic – being both hydrophilic and hydrophobic. As the tail is made of fatty acids, it does not form hydrogen bonds with water and therefore is hydrophobic and non-polar. If the chain contains a cis double bond then the chain is kinked – therefore reducing the tight packing of the membrane and so increasing its movement.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |