Question

Imagine two lipid bilayers. In one, all the hydrocarbon chains are saturated (no double bonds). In the other, all the hydrocarbon chains are unsaturated (with cis-double bonds). Which one of the following predictions about their fluidity and permeability to water-soluble molecules would be most accurate?

1) The bilayer with saturated chains would be more fluid and more permeable.
2) The bilayer with saturated chains would be less fluid and less permeable.
3) The bilayer with unsaturated chains would be less fluid and more permeable.
4) The bilayer with unsaturated chains would be more fluid and less permeable.

Answer 1

The lipid bilayer with unsaturated hydrocarbon chains would be more fluid and more permeable due to the kinks introduced by cis-double bonds, which prevent tight packing of the chains.

Step-by-step explanation:

The prediction that would be most accurate about the fluidity and permeability of lipid bilayers with different types of hydrocarbon chains is that the bilayer with unsaturated chains would be more fluid and more permeable. This is because unsaturated fatty acids have cis-double bonds that introduce kinks in the hydrocarbon tails, preventing the chains from packing tightly together. This loose packing results in increased membrane fluidity and more space between the molecules, which may increase the permeability to water-soluble molecules. In contrast, saturated fatty acids have straight tails that pack closely together, making the membrane less fluid and less permeable.