What type of molecules are known to repel water in biological systems?

What type of molecules are known to repel water in biological systems?

• A. Hydrophilic molecules
• B. Amphipathic molecules
• C. Hydrophobic molecules
• D. Electrolytes

Answer: (C)

Hydrophobic molecules are characterized by their inability to mix with or be dissolved in water. This property arises from their nonpolar nature, which means they do not have charged regions that can interact with the polar molecules of water. In biological systems, these molecules often play essential roles, such as forming cell membranes where they create a barrier that separates the internal environment of a cell from the external environment. The hydrophobic effect leads to the aggregation of these molecules in aqueous solutions, promoting the formation of structures like lipid bilayers. In contrast, hydrophilic molecules easily interact with water due to their polar or charged groups that can form hydrogen bonds with water molecules, making them well-suited to be dissolved in water. Amphipathic molecules contain both hydrophilic and hydrophobic regions, allowing them to interact with both water and lipids, but they do not exclusively repel water. Electrolytes, which are ions that can conduct electricity in solution, are also hydrophilic due to their ability to interact with water molecules. Hence, hydrophobic molecules stand out as the correct answer in this context.

Hydrophobic molecules are characterized by their inability to mix with or be dissolved in water. This property arises from their nonpolar nature, which means they do not have charged regions that can interact with the polar molecules of water. In biological systems, these molecules often play essential roles, such as forming cell membranes where they create a barrier that separates the internal environment of a cell from the external environment. The hydrophobic effect leads to the aggregation of these molecules in aqueous solutions, promoting the formation of structures like lipid bilayers.

In contrast, hydrophilic molecules easily interact with water due to their polar or charged groups that can form hydrogen bonds with water molecules, making them well-suited to be dissolved in water. Amphipathic molecules contain both hydrophilic and hydrophobic regions, allowing them to interact with both water and lipids, but they do not exclusively repel water. Electrolytes, which are ions that can conduct electricity in solution, are also hydrophilic due to their ability to interact with water molecules. Hence, hydrophobic molecules stand out as the correct answer in this context.