Cell Membrane Functions and Structure

Cell Membrane Structure and Function

• The primary function of the cell membrane is to regulate what enters and leaves the cell.

Fluid Mosaic Model

• The fluid mosaic model describes the structure of the cell membrane, proposing that it is a dynamic and flexible structure composed of a phospholipid bilayer embedded with proteins.

Phospholipid Bilayer

• The phospholipid bilayer is the 'main fabric' of the cell membrane, composed of two layers of phospholipid molecules with their hydrophilic heads facing outwards and hydrophobic tails facing inwards.

Discovery of the Cell Membrane Structure

• In 1925, Evert Gorter and Francois Grendel discovered that the cell membrane is composed of a lipoid (fat-like) substance.

Homeostasis

• Homeostasis refers to the ability of an organism to maintain a stable internal environment despite changes in the external environment.

Integral and Peripheral Proteins

• Integral proteins are embedded within the phospholipid bilayer and can transport molecules across the cell membrane.
• Peripheral proteins are attached to the outer or inner surface of the cell membrane and can participate in cellular signaling and cell-cell interactions.

Cholesterol Function

• Cholesterol helps maintain the integrity and fluidity of the cell membrane by filling gaps between phospholipid tails and modulating the fluidity of the membrane.

Carbohydrates in the Cell Membrane

• Carbohydrates are attached to proteins or lipids in the cell membrane, forming glycoproteins and glycolipids, which play roles in cell-cell recognition and signaling.

Passive Transport

• Passive transport across cell membranes involves the movement of molecules from an area of high concentration to an area of low concentration, without the use of energy.

Osmosis

• Osmosis is the process of water molecules moving through a selectively permeable membrane from an area of high concentration to an area of low concentration.

Facilitated Diffusion

• Facilitated diffusion is a type of passive transport that involves the movement of molecules through the cell membrane with the assistance of transport proteins.