Water can move passively through a membrane by moving through the pores of a cell. Other substances cannot move through a cell membrane.
Two substances that move passively through the lipid part of the membrane are fat and oxygen. Other substances include steroids and carbon dioxide.
Cytoplasm is the liquid substance in a cell.
passive transport pump
Lipid molecule
Facilitated diffusion uses proteins to move a molecule across the cell membrane without energy.
Facilitated diffusion
Facilitated diffusion
A large cell will never move across an intact cell membrane.
Cheese toast
Facilitated diffusion uses proteins to move a molecule across the cell membrane without energy.
Lipid molecule
Facilitated diffusion uses proteins to move a molecule across the cell membrane without energy.
active transport
Active transport
Active transport
active transport
carrier proteins
Active transport
Facilitated diffusion
Facilitated diffusion