[Campbell Biology P.123] Why do phospholipids spontaneously form a bilayer in an aqueous env... | Practice Question

Why do phospholipids spontaneously form a bilayer in an aqueous environment?

  • A: Their hydrophobic heads are attracted to water, while hydrophilic tails repel water.
  • B: Their hydrophilic heads cluster together, while hydrophobic tails face the aqueous environment.
  • C: Their hydrophilic heads are attracted to water, and their hydrophobic tails associate with each other, shielded from water.
  • D: They form a single layer to maximize exposure of all parts to water.

Explanation

Phospholipids are amphipathic molecules, meaning they have both hydrophilic water-loving and hydrophobic water-fearing parts. In an aqueous environment, their hydrophilic phosphate heads are attracted to water, while their hydrophobic fatty acid tails spontaneously associate with each other to minimize contact with water. This arrangement leads to the formation of a bilayer, where the tails are shielded in the interior, and the heads face the aqueous surroundings on both sides, forming a stable structure like a cell membrane.