Essay about A Study On Cell Membrane

1071 Words Sep 11th, 2016 5 Pages
According to Biology in Focus: Second Edition the cell membrane is selectively permeable to allow certain substances through, but not all substances. (Campbell Biology Focus, 2014). In other words, the cell membrane’s purpose is to protect the cell from unwanted, outside substances. It is a combination of fluids comprised of lipids, proteins, and carbohydrates. The most abundant lipid found in membranes are phospholipids, which have a polar or a hydrophilic head facing out towards the hydrophilic regions and a nonpolar or hydrophobic tail that face in to the hydrophobic region. A membrane is composed of two layers of these phospholipids, the lipid bilayer, in which the tails face one another and the heads face outwards. These lipids can also be saturated or unsaturated, which will affect the fluidity of the cell membrane. If a membrane is composed of saturated lipids than there will be a lower fluidity than the membranes composed of more unsaturated lipids. This is due to the fact that when the lipids are saturated, the tails are tightly packed into a straight line. Because they are so tightly packed, there is little space to allow substances to pass through. When the lipids are unsaturated they are not so tightly packed and have a kink in the structure. This kink creates more space to allow substances to pass through. Temperature can also effect fluidity; the higher the temperature, the higher the fluidity. When the temperature is lower it inhibits fluidity to a…

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