Active and Passive Transport

Passive Transport

• Movement of substance through the cell membrane without the input of energy

• Three types– Diffusion– Osmosis– Facilitated diffusion

Diffusion

• The random movement of molecules from an area where there is relatively fewer of them

• Continues to happen until the amount in both areas is equal =EQUILIBRIUM

Osmosis

• Osmosis= the diffusion of water through a cell membrane

Facilitated Diffusion

• Facilitated diffusion- transport proteins in the cell membrane are used to move substances in and out of the cell– For example: Glucose

molecules are too big to enter without the help of transport proteins

Active Transport

• Sometimes a substance needs to enter a cell even though there is a greater amount of that substance outside the cell than inside– Cell needs energy to move the substance inside

• Active transport- when an input of energy is required to move materials through a cell membrane– Involves proteins

How it Works

• Active transport requires transport proteins, which bind with the needed particle and cell energy is used to move it through the membrane

Active Transport

Let’s Review!

Endocytosis

• Some molecules or substances are too BIG for diffusion or transport proteins

• The cell membrane must fold in on itself, enclosing the substance in a vesicle

• The vesicle pinches off and enters the cytoplasm, acting as a transport and storage structure

• This process is call ENDOCYTOSIS

Exocytosis

• How the cell releases what’s in the vesicle• The OPPOSITE of endocytosis• The vesicles membrane fuses with the cell

membrane’s, and the vesicle contents are released

• Video time!

Exit Ticket

• Compare and contrast facilitated diffusion and active transport.

• Do you have any questions or things you don’t understand?