Question

Membrane lipids have fatty acid tails and, like triacylglycerols, their properties are governed by the properties of these tails. Based on what we saw with dietary lipids, which membrane would have more fluid characteristics – the one with more saturated fatty acids or the one with more unsaturated fatty acids? Explain your reasoning.

Look at the structure of cholesterol. Cholesterol is a necessary component of biological membranes. What do you think cholesterol would do to the structure of a membrane – make it more solid or more fluid? Why?

Answer 1

Question 1

The membrane with more unsaturated fatty acid will be more fluid chracterstic as compare to the with more saturated fatty acid. This is because kinks present in the unsaturated fatty acid prevent the tight packing between the fatty acid tails and therefore provide more fluidity.

Figure: Kinks in the unsaturated fatty acid

Question 2

The cholestrol contribution to the fluidity of the plasma membrane is dependent on the temperature. At the lower temperature, cholestrol decreases the membrane fluidity because it intercalate between the phospholipid and thus prevent them from stiffening . On the other hand at high temperature, it increases the fluidity of the membrane to stabilize the structure of membrane.