Cellular Transport

Diffusion- net movement of particles from an area of many particles to an area of fewer particles.

Concentration- amount of a substance in a particular area. The substances diffuse from areas of high concentration to low concentration.

Dynamic Equilibrium- where there is continuous movement but no overall change.

Facilitated Diffusion- uses transport proteins to move other ions and small molecules across the plasma membrane.

2 Types of Transport Proteins

1. Channel proteins- moves substances through the cell. It opens and closes.

2. Carrier proteins- changes its shape as the substance moves through the cell. It helps in movement.

Osmosis- the diffusion of water.

Water is an universal solvent.

Isotonic solution- Iso is Greek for equalThe cell has equal amounts of water and solutes. The cell will retain its normal shape.

Hypotonic solution- Hypo is Greek for under.The cell has less water inside than outside. There is more solute. Water will move into the cell causing it to swell and burst.

Hypertonic solution- Hyper is Greek for above.The cell has more water inside than outside. There is less solute. Water will move out of the cell causing it to shrink. In plants, it's called wilting.

Active Transport- movement of substances from a lower concentration to a higher concentration. Since the movement across the plasma membrane is against the concentration gradient, it requires energy.

Sodium/potassium pump- One common active transport pump found in animal cells. It maintains the level of Sodium and Potassium inside and outside the cell. The pump uses energy (ATP) to move 3 sodium ions out while moving 2 potassium ions in.

Transportation of Large Particles

Endocytosis- process where the cell encloses the large particle in a portion of the plasma membrane. When the large particle with the plasma membrane moves inside the cell, it is called a vacuole.

Exocytosis- is the secretion of materials (wastes) from the cell. It is the reverse of endocytosis.

Both endocytosis and exocytosis requires energy.