A Level Biology Practice Exam

What is the basic structure of a phospholipid molecule?

1. One glycerol, one fatty acid, and two phosphate groups

2. One glycerol, two fatty acids, and one phosphate group

3. Two glycerol and one fatty acid

4. One glycerol and three fatty acid chains

The correct answer is: One glycerol, two fatty acids, and one phosphate group

The basic structure of a phospholipid molecule consists of one glycerol backbone, two fatty acid tails, and one phosphate group. This unique arrangement allows phospholipids to be amphipathic, meaning they have both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties. The glycerol provides a point of attachment for the fatty acids and the phosphate group. The two fatty acid chains are typically composed of long hydrocarbon tails, which are hydrophobic and help to form the lipid bilayer in cellular membranes. In contrast, the phosphate group is hydrophilic and can interact with water, making one end of the phospholipid molecule attracted to aqueous environments. This structural characteristic is crucial for maintaining the integrity of cell membranes, allowing them to function effectively as barriers while facilitating communication and transport across the membrane.