Phospholipid

Definition

Phospholipids are a class of lipids that form the fundamental structure of cell membranes. They consist of two hydrophobic fatty acid tails and a hydrophilic phosphate head.

5 Must Know Facts For Your Next Test

1. Phospholipids are amphipathic molecules, meaning they have both hydrophilic and hydrophobic parts.
2. The bilayer formation of phospholipids is crucial for creating the semi-permeable nature of cell membranes.
3. In aqueous environments, phospholipids spontaneously form bilayers with the hydrophobic tails facing inward and the hydrophilic heads facing outward.
4. Phospholipids can move laterally within the membrane but rarely flip-flop between layers.
5. They play a key role in membrane fluidity, which is essential for various cellular processes such as signaling and transport.

Review Questions

• What structural feature allows phospholipids to form bilayers in cell membranes?
• Why are phospholipids described as amphipathic molecules?
• How do phospholipid molecules contribute to membrane fluidity?

Related terms

Lipid Bilayer:

A double layer of phospholipids that makes up plasma and organelle membranes.

Amphipathic Molecule: A molecule containing both hydrophobic and hydrophilic regions.

Membrane Fluidity:

The viscosity of the lipid bilayer that allows for mobility and flexibility within the cell membrane.