Lecture 3-1: The Lipid Bilayer

Lipid Bilayer

A membrane structure consisting of two layers of phospholipids, which creates a barrier between the interior of a cell and the external environment.

Phospholipid

A type of lipid molecule that consists of a hydrophilic (water-attracting) head and two hydrophobic (water-repelling) tails, forming a bilayer in cellular membranes.

Amphipathic

Referring to a molecule that has both hydrophilic and hydrophobic parts, enabling it to interact with both water and fats.

Bilayer Sphere Formation

The process by which lipid bilayers spontaneously form spherical shapes to minimize hydrophobic interactions with water.

Fluidity

The degree of movement and flexibility of lipids within a membrane; affected by temperature and lipid composition.

Transmembrane Proteins

Proteins that span across the lipid bilayer of a membrane, crucial for transport and communication across the membrane.

Flippases

Enzymes that facilitate the transfer of phospholipids from one leaflet of a membrane bilayer to another, maintaining membrane asymmetry.

Glycocalyx

A sugar-rich coating on the extracellular surface of membranes formed by glycolipids and glycoproteins.

Apoptosis

The process of programmed cell death, often indicated by the flipping of phosphatidylserine to the outer leaflet of the plasma membrane.

Scramblase

An enzyme that randomizes the distribution of phospholipids between the inner and outer leaflets of a bilayer during membrane assembly.