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
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
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!