Question

Phospholipids, molecules found within a cell membrane, have hydrophobic tails and hydrophilic heads. These regions act in the same manner that hydrophobic and hydrophilic amino acids act. When phospholipids are found as a sphere in a glass of water, which of the following would you expect:

Answer 1

The correct answer is "The hydrophilic heads will point toward the water, and the hydrophobic tails will point away from the water".

Step-by-step explanation:

The missing options of this question are:

a. The hydrophobic tails will point toward the water, and the hydrophilic heads will point away from the water.

b. The hydrophilic heads will point toward the water, and the hydrophobic tails will point away from the water.

c. Hydrophilic heads and hydrophobic tails will both point toward the water.

d. The hydrophobic tails and hydrophilic heads will be arranged randomly.

The correct answer is option b. Phospholipids are amphiphilic molecules that have hydrophilic heads and hydrophobic tails. This characteristic makes them the main component of cell's membrane where the hydrophilic tails point outside and inside the cell, and the hydrophobic tails point within the membrane. If phospholipids are found as a sphere in a glass of water, the hydrophilic heads will point toward the water, and the hydrophobic tails will point away from the water. This is the most stable structure, therefore, this will be the arrangement of the phospholipids.