Cell Membrane Structure and Function

Overview

This lecture explains the structural components of the cell membrane, their arrangement, and their roles in cellular function and transport.

The cell membrane is primarily composed of a phospholipid bilayer.
Phospholipids have hydrophilic heads (water-attracting) and hydrophobic tails (water-repelling).
The bilayer arrangement allows the membrane to be selectively permeable.

Integral proteins span the membrane and assist in transport and signaling.
Peripheral proteins are attached to the membrane surface and help with cell recognition and structure.
Glycoproteins act as identification tags for cellular interactions.

Carbohydrates attach to lipids (glycolipids) or proteins (glycoproteins) for cell recognition.
Cholesterol molecules within the membrane provide stability and fluidity control.

The membrane controls entry and exit of substances (selective permeability).
It protects the cell’s internal environment and supports communication with other cells.
Membrane proteins facilitate transport through channels, carriers, and pumps.

The fluid mosaic model describes the membrane as flexible with proteins embedded in a shifting sea of lipids.
This model explains the dynamic nature and adaptability of the membrane.

Phospholipid Bilayer — Two layers of phospholipids forming the fundamental structure of the cell membrane.
Hydrophilic — Attracted to water; describes the heads of phospholipids.
Hydrophobic — Repelled by water; describes the tails of phospholipids.
Integral Protein — Protein embedded within the membrane, involved in transport.
Peripheral Protein — Protein attached to membrane surface, aiding in support and recognition.
Glycoprotein — Protein with attached carbohydrate, used for cell identification.
Selective Permeability — Allowing only certain substances to cross the membrane.
Fluid Mosaic Model — Concept that describes the flexible, varied arrangement of molecules in the membrane.