Phospholipid bilayer definition biology. Phospholipid bilayer in the largest biology dictionary online. Dec 4, 2025 · Each phospholipid molecule possesses a dual nature, described as amphipathic. Figure 3 5 2 1: Phospholipid Bilayer: The phospholipid bilayer consists of two adjacent sheets of phospholipids, arranged tail to tail. However, the cell membrane also contains other macromolecules like membrane proteins, and carbohydrates. In this unit, we will explore the structure and function of the phospholipid bilayer. These bilayers create a semi-permeable barrier that separates the interior of a cell from its external environment, allowing for the regulation of substances in and out of the cell while maintaining homeostasis. Phospholipids are amphipathic molecules consisting of a polar, hydrophilic ‘head’ region formed by a phosphate group and the non-polar hydrophobic ‘tail’ consisting of two long chain fatty acids. It acts as a semi-permeable barrier, allowing cells to regulate what enters and exits, and helps to maintain the proper balance of ions and other substances within the cell. In biology, amphipathic molecules are important in the formation of biological membranes and micelles. The structure of the cell membrane, particularly its phospholipid bilayer and embedded proteins, allows it to effectively regulate substance movement. rvy ryp lvvgii esgj btdb fgm zrfjv xlviy tbhshg bsuwt