Cell Membrane Structure and Function

This set explores the structural components, various membrane proteins, historical models, and essential functions of the cell membrane.

Cell Membrane

A thin layer that separates the cell from its external environment and regulates the passage of substances into and out of the cell.

Phospholipid Molecule Components

Consists of a charged phosphate group, glycerol, and two fatty acid chains.

Hydrophilic Head

The polar part of a phospholipid containing glycerol and a charged phosphate group that can form hydrogen bonds with water.

Hydrophobic Tail

The nonpolar part of a phospholipid made of two fatty acid chains that are repelled by water and face inward.

Cholesterol

A membrane component that strengthens the membrane, making it flexible but not less fluid, and reduces permeability to water-soluble substances.

Carbohydrates

Identification tags attached to membrane proteins that enable cells to distinguish one type of cell from another.

Transport Proteins

Membrane proteins that help materials cross the cell membrane.

Channel Proteins

Proteins that form tunnels to help cells import or export needed materials and expel wastes.

Cell Recognition Proteins (Glycoprotein)

Proteins that enable cells to distinguish their own cells from foreign organisms, such as pathogens.

Cytoskeleton Proteins

Proteins that act as muscle and skeleton to maintain cell shape and motility.

Alpha-helix (Junction) Protein

Proteins that assist in cell-to-cell adhesion and communication between cells.

Globular (Receptor) Proteins

Proteins that facilitate the exchange of signals with other cells by changing shape to allow a ligand to bind to it.

Ligand

A specific molecule that binds to a globular (receptor) protein to initiate signal exchange.

Peripheral Protein

Proteins that provide support, communication, and molecule transfer; they may or may not be attached to integral proteins.

Enzymatic Proteins

Proteins that catalyze or carry out chemical reactions within the cell membrane.

Classical Plasma Membrane Model

Proposed by James Daniell and Hugh Davson, hypothesizing that the cell is covered by a thin, flexible envelope of phospholipid bilayer and proteins.

Fluid Mosaic Model

Proposed by Jonathan Singer and Garth Nicholson (1972), describing the membrane as flexible (fluid-like) with a mosaic-like variety of molecules.

Gatekeeper

A functional role of the cell membrane in regulating the passage of important molecules, ions, and gases.