The presence of double bonds in the fatty acids would make the cell membrane less permeable to polar molecules.
1. Double bonds in the fatty acid chains introduce kinks in the structure of the lipid bilayer. This kink makes it more difficult for polar molecules to pass through the membrane.
2. As a result, the cell membrane becomes less fluid and less permeable to polar substances like water and ions.
3. In contrast, increasing the length of the hydrocarbon chains would increase membrane fluidity, making it more permeable to polar molecules.
In summary, the presence of double bonds in the fatty acids of the cell membrane would reduce its permeability to polar molecules by introducing structural constraints that hinder the movement of these substances across the membrane.
