Question

The cell membrane has____. a) polar heads on the outside and nonpolar fatty acids on the inside b) nonpolar fatty acids on the outside and a polar heads on the inside c) polar heads on both inside and outside d) nonpolar fatty acids on both inside and outside

Answer 1

a) polar heads on the outside and nonpolar fatty acids on the inside

Explanation:

The cell membrane is made up of phospholipids arranged in a bilayer, where hydrophilic polar (negatively-charged) heads of phospholipids interact with water molecules (i.e., aqueous surrounding media). Moreover, non-polar (uncharged) fatty acid tails are hydrophobic because they cannot be dissolved in water. Thus, the bilayer cell membrane is a structure where non-polar fatty acid chains are localized in the inner region (away from the water), while hydrophilic phosphate heads face outward, interacting with water on both sides of the cell membrane.