Part 3: Homeostasis and Cell Transport (Chapter 5)

Passive Transport

• NO ENERGY REQUIRED to move substances across membrane from a higher concentration to a lower concentration

• Types:1. Diffusion2. Osmosis3. Facilitated Diffusion4. Diffusion through Ion Channels

•Involves the movement of molecules across the cell membrane without an input of energy by the cell.

Which types of molecules can move through the membrane

without energy?• Small, nonpolar (hydrophobic) molecules

• Examples: O2, CO2, H2O, lipids

Diffusion

Osmosis

Hypotonic Isotonic Hypertonic

Facilitated Diffusion

Ion Channels

• Active transport • moves molecules across the cell

membrane from an area of lower concentration to an area of higher concentration (against concentration gradient)

• requires cells to use ENERGY (ATP)• Some types of active transport are

performed by carrier proteins called cell membrane pumps.

Active TransportCell Membrane Pumps and Vesicles

Example: Sodium-Potassium Pump

Sodium-Potassium Pump

Endocytosis and

Exocytosis