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Passive TransportPassive transport is a type of transport which does not require the cell to use energy to move materials from one place to another. Materials usually move from a place of high concentration to an area of low concentration. There are four kinds of passive transport:
Diffusion: non-polar particles are able to diffuse from an area of high concentration across a membrane to an area of low concentration. Osmosis: the diffusion of water from a hypotonic solution (low solute in high water concentration) across a semipermeable membrane, to a solution that is hypertonic (high solute in low water concentration). When there is an equivalent concentration of water and solute, the solution is called an isotonic solution. Blood Cell vs Plant Cell is a Isotonic/Hypotonic/Hypertonic Solution. Facilitated Diffusion: the movement of molecules/particles through a cell protein channel/pore. Bulk Transport: the movement of solutes being carried along with moving liquid in one general direction. Active TransportActive transport, the opposite of passive transport, does require the cell to use energy to move materials from one place to another. In active transport, materials move from a place of low concentration to an area of high concentration. There are three types of active transport:
Protein Pumps: found on the cell membrane, protein pumps use energy in the form of ATP (adenosine triphosphate) to change their shape and to pump molecules in or out of the cell. Endocytosis: when a cell surrounds and wraps a particle with it's membrane, "swallowing" the particle inside. This processes can be split into two different definitions: Phagocytosis- the ingesting of solid materials. Pinocytosis- the ingesting of liquid materials. Exocytosis: when particles, wrapped in a membranous sac, are dumped out outside the cell because the membranous sac blends in with the plasma membrane. |
The above gif is an example to how a protein pump works. After a specific molecule(s) enters the protein, it waits until a molecule of ATP comes by and attaches itself to the protein, giving the protein energy to change it's shape and to release the molecule(s) that were inside the protein. The protein stays in that new shape, as a phosphate ("P") is left attached to the protein from inside the cell. The protein only goes back to it's original form after the phosphate detaches itself, providing a way for outside molecules a chance to enter inside the cell.
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