Types of movement
- small and non-polar lipid soluble molecules
- directly through phospholipid bilayer
- net movement down concentration gradient
- As diffusion but requiring a channel protein in the membrane to allow the diffusion of polar molecules, charged and water-soluble groups.
- essentially the diffusion of free water molecules
- net movement of free water molecules from a solution with lower solute concentraion to a solution with a higher solute concentration
- movement through a partially permeable membrane.
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- all kinds of molecules possible
- through carrier proteins
- active- needs energy from the breakdown of ATP
- up a concentration gradient
Exo-(out of cell) and endocytosis (into cell):
- large particles of all kinds
- bulk transport involving vesicles made from cell surface membrane in endocytosis, and fusing with the cell surface membrane in exocytosis.
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