Biology- Unit 2: Section 2: Cell Transport

Homeostasis

Need of an organism to stay stable

Passive Transport

Requires no extra energy by the cell because the molecules move from high concentration to low concentration.

Active Transport

Requires energy (ATP) because the molecules are moving from low concentration to high concentration.

Solute

What gets dissolved

Solvent

What does the dissolving

Solution

A uniform mixture of two or more substances

Concentration

The amount of solute dissolved in the solvent

Simple Diffusion

PASSIVE- The spreading out of molecules across a membrane until equilibrium is reached. Example: O2 and CO2 and other small, nonpolar molecules. Molecules move down the concentration gradient.

Facilitated Diffusion

PASSIVE- A transport protein that helps to facilitate the diffusion of molecules that normally couldn't pass through the cell membrane. Molecules move down the concentration gradient.

Osmosis

PASSIVE- The simple diffusion of water across the cell membrane. Water molecules move down a concentration gradient from high water to low water until equilibrium is reached.

High water concentration

Low solute concentration

Low water concentration

High solute concentration

What are the three types of osmosis?

Hypertonic, hypotonic and isotonic solutions.

Hypertonic

Water concentration is lower that the cell's cytoplasm. Cell shrivels

Hypotonic

Water concentration is higher than the cell's cytoplasm. Cell swells

Isotonic

Identical water concentration to cell cytoplasm. Cell stays the same

Molecular Pumps

ACTIVE- When a cell uses energy to pump molecules across the membrane against the concentration gradient through a protein channel.

Endocytosis

ACTIVE- Uses vesicles to move large particles into the cell.

Exocytosis

ACTIVE- Uses vesicles to export materials out of the cell.

Phagocytosis

Cell eating. Cell engulfs solids into vesicles and "digests" them.

Pinocytosis

Cell drinking. Cell engulfs liquids into vesicles and "digests" them.