In the context of the lipid bilayer, which part of a phospholipid molecule is hydrophobic?

• A. The phosphate-containing head group
• B. The glycerol backbone
• C. The fatty acid (hydrocarbon) tails
• D. The polar head region as a whole

Answer: (C)

Verified step by step guidance

1. Understand the structure of a phospholipid molecule, which consists of a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tails.
2. Identify the components of the phospholipid: the phosphate-containing head group, the glycerol backbone, and the fatty acid (hydrocarbon) tails.
3. Recall that the phosphate-containing head group is polar and interacts well with water, making it hydrophilic.
4. Recognize that the glycerol backbone connects the head group to the tails but is not the primary hydrophobic part.
5. Conclude that the fatty acid (hydrocarbon) tails are nonpolar and hydrophobic, meaning they avoid water and form the interior of the lipid bilayer.