Cell Membrane Structure and Functions

Study Notes

Cell Membrane Structure

Phospholipid bilayer: composed of two layers of phospholipid molecules with their hydrophobic (non-polar) tails facing inward and hydrophilic (polar) heads facing outward
Thickness: approximately 7-10 nanometers (nm)
Semipermeable: allows certain molecules to pass through while keeping others out

Cell Membrane Functions

Regulates what enters and leaves the cell
Maintains cell shape and provides mechanical support
Acts as a barrier against external substances
Plays a role in cell signaling and communication

Cell Membrane Components

Phospholipids: amphipathic molecules that make up the majority of the bilayer
Proteins: embedded in the bilayer, facilitate transport, signaling, and cell-cell interactions
Cholesterol: helps maintain membrane fluidity and structure
Carbohydrates: attached to proteins and lipids, involved in cell-cell recognition and signaling

Cell Membrane Transport

Passive transport: movement of molecules from high to low concentration without energy input
- Diffusion: movement of molecules from high to low concentration
- Osmosis: movement of water molecules through the membrane
Active transport: movement of molecules from low to high concentration using energy input
- Carrier proteins: transport molecules across the membrane
- Pumping mechanisms: use energy to move molecules against their concentration gradient

Fluid Mosaic Model

Describes the cell membrane as a dynamic, fluid structure with proteins and lipids able to move laterally
Supports the idea of a semi-fluid membrane that allows for membrane transport and cellular processes

Description

Test your knowledge of cell membrane structure, functions, and transport mechanisms. Learn about phospholipid bilayer, protein, and cholesterol composition, as well as passive and active transport processes. Understand the fluid mosaic model and its significance in cellular biology.