Passive Transport

Cellular Transport Mechanism

The processes by which molecules cross the cell membrane.

High Permeability

Molecules like Carbon Dioxide and Oxygen that easily cross the cell membrane.

Moderate Permeability

Molecules such as Water and Urea that can cross the cell membrane with some difficulty.

Low Permeability

Glucose (C6H12O6), which has limited ability to cross the cell membrane.

Very Low Permeability

Molecules like Ions, Amino acids, Nucleic acids, and Proteins that cannot easily cross the cell membrane.

Passive Transport

Movement of molecules from high to low concentration without energy expenditure by the cell.

Active Transport

Movement of molecules against the concentration gradient, requiring energy.

Bulk Transport

The process of moving large quantities of materials across the cell membrane.

Concentration Gradient

The difference in the concentration of molecules at two points, influencing their movement.

Simple Diffusion

The process where a single substance moves from high to low concentration until equilibrium is reached.

Factors Affecting Diffusion

Variables such as concentration gradient, mass of molecules, temperature, solvent density, solubility, surface area, and distance that influence the rate of diffusion.

Osmosis

The movement of water through a semipermeable membrane from higher to lower concentration.

Tonicity

The effect of an extracellular solution on the volume of a cell through osmosis.

Osmolarity

The total solute concentration of a solution.

Isotonic Solution

A solution with equal osmolarity to the cell, resulting in no net water movement.

Hypotonic Solution

A solution with lower osmolarity than the cell, causing water to enter the cell.

Hypertonic Solution

A solution with higher osmolarity than the cell, leading to water leaving the cell.

Facilitated Diffusion

The process where substances are transported across the membrane with the help of proteins.

Transport Proteins

Proteins that assist in the movement of materials across the cell membrane.

Channel Proteins

Proteins embedded in the membrane that provide a pore for materials to cross.

Carrier Proteins

Proteins that change shape to transport materials from one side of the membrane to the other.