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Phospholipid Bilayers - avoiding the water The polar...

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Phospholipid Bilayers Phospholipids spontaneously form a bilayer in a watery environment. They arrange themselves so that the polar heads are oriented toward the water and the fatty acid tails are oriented toward the inside of the bilayer (see the diagram below). In general, nonpolar molecules do not interact with polar molecules. This can be seen when oil (nonpolar) is mixed with water (polar). Polar molecules interact with other polar molecules and ions. For example table salt (ionic) dissolves in water (polar). The bilayer arrangement shown below enables the nonpolar fatty acid tails to remain together,
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Unformatted text preview: avoiding the water. The polar phosphate groups are oriented toward the water. Flexibility The fatty acid tails are flexible, causing the lipid bilayer to be fluid. This makes the cells flexible. At body temperature, membranes are a liquid with a consistency that is similar to cooking oil. Cholesterol In animals, cholesterol is a major membrane lipid. It may be equal in amount to phospholipids. It is similar to phospholipids in that it one end is hydrophilic , the other end is hydrophobic . Cholesterol makes the membrane less permeable to most biological molecules....
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