Fatty acids are organic compounds that consist of two parts: a part that likes H2O and a part that does not like H2O.
The correct answer and explanation is:
Fatty acids are long-chain hydrocarbons with a carboxyl group (-COOH) at one end. The carboxyl group contains a hydrophilic (water-loving) portion, which is polar, and the hydrocarbon chain, made of carbon and hydrogen atoms, is hydrophobic (water-repellent) because it is nonpolar. This dual characteristic, having both a hydrophilic and hydrophobic part, is known as amphipathic.
The hydrophilic part of the fatty acid is the carboxyl group, which is polar and forms hydrogen bonds with water molecules. The hydrophobic part is the long hydrocarbon tail, which is nonpolar and avoids interactions with water molecules. This structure enables fatty acids to interact with both water and lipids, making them essential components of biological membranes.
In an aqueous environment, fatty acids tend to form structures that minimize the contact between the hydrophobic tail and water. For example, in a solution, they may arrange themselves into micelles or bilayers, with the hydrophobic tails pointing inward and the hydrophilic heads facing outward toward the water. This property is crucial for the formation of cell membranes, where phospholipids, which are similar to fatty acids but with a phosphate group replacing one of the fatty acid tails, organize into a bilayer with the hydrophilic heads exposed to the water and the hydrophobic tails forming a barrier to water-soluble substances.
The amphipathic nature of fatty acids is essential in biological systems, as it allows them to form structures that are selectively permeable to certain molecules, a critical function in cellular processes such as signal transduction and nutrient transport. Fatty acids are also involved in energy storage, and their hydrophobic properties make them efficient in storing energy in the form of fats (triglycerides).