Molecules that have properties of both polar and nonpolar molecules are called

Multiple Choice

A hydrophobic.

B hydrophilic.

C amphipathic.

D unipolar.

E bipolar.

The correct answer and explanation is:

The correct answer is C. amphipathic.

An amphipathic molecule is one that has both polar and nonpolar regions within its structure. This dual characteristic allows it to interact with both hydrophilic (water-loving) and hydrophobic (water-fearing) substances. The nonpolar regions are typically hydrophobic and avoid water, while the polar regions are hydrophilic and interact well with water. A common example of an amphipathic molecule is a phospholipid, which is a major component of cell membranes.

Phospholipids have a hydrophilic “head” that is attracted to water and hydrophobic “tails” that repel water. This property allows them to form bilayers in aqueous environments, with the hydrophobic tails facing inward, shielded from water, and the hydrophilic heads facing outward, interacting with the surrounding aqueous environment. This arrangement is crucial in the formation of biological membranes, where the amphipathic nature of phospholipids helps to create a stable barrier that separates the inside of the cell from the outside.

The other options are incorrect for the following reasons:

• A. Hydrophobic refers to substances that repel water and only interact with nonpolar substances.
• B. Hydrophilic refers to substances that are attracted to water and interact easily with polar substances.
• D. Unipolar and E. Bipolar are not terms used to describe molecules with both polar and nonpolar regions.

Understanding the amphipathic nature of molecules is essential in biochemistry, particularly when studying cell membranes, protein structure, and the behavior of molecules in different solvents.