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Unit 6. Cell Transport Part 2. Facilitated Diffusion. Carrier protein in the cell membrane is needed to help move a specific molecule across Facilitated means to help or make easier Carrier protein acts like a gate and increases the rate of transport of certain substances
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Unit 6 Cell Transport Part 2
Facilitated Diffusion • Carrier protein in the cell membrane is needed to help move a specific molecule across • Facilitated means to help or make easier • Carrier protein acts like a gate and increases the rate of transport of certain substances • Does not require energy because molecules are moving down the concentration gradient
Active Transport • Movement of a substance against the concentration gradient from low to high concentration • Movement of molecules that can't cross the cell membrane • Energy is needed and work is done for this type of transport • This is one of the most important uses of our cell energy!
Endo- and Exo-cytosis • Movement of very large molecules (food, waste) into (endo) and out (exo) of the cell • The large molecule is enclosed in a "packet" • To move into – part of cell membrane surrounds molecule to form a "packet", then pinches off the cell membrane, entering the cell • To move out – a "packet" (the molecule surrounded by a membrane) fuses/merges with the cell membrane – molecule released outside the cell
Exocytosis and Endocytosis Exocytosis Exo = Out leaves the cell Endocytosis Endo = In enters the cell