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6 Cards in this Set
- Front
- Back
Active transport
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The movement of molecules or ions into or out of a cell from a region of lower concentration to a region of higher concentration using ATP and carrier proteins. |
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ATP and active transport
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ATP is used to: - directly move molecules individually move molecules using a concentration gradient. - individually move molecules using a concentration gradient which has already been set up by active transport (co-transport). |
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Active transport differs from passive forms of transport, why?
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1) Metabolic energy in the form of ATP is needed. 2) Substances are moved against a concentration gradient, low to high. 3) Carrier protein molecules act as 'pumps'. 4) The process is very selective, with specific substances being transported. |
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How active transport works
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2) The molecule or ion binds to receptor sites on the carrier protein. 3) On the inside of the cell, ATP binds to the protein causing it to split into ADP and a phosphate molecule. Due to this the protein molecule changes shape and opens to the opposite side of the membrane. 4) The molecule or ion is then released to the other side of the membrane. 5) The phosphate molecules is released from the protein which causes the protein to revert to its original shape, ready for the process to be repeated. The phosphate molecule recombines with the ADP to form ATP during respiration. |
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Sodium-potassium pump |
Here, the sodium ions are actively removed from the cell/organelle while potassium ions are actively taken in from the surroundings. This process is important to an number of processes, including the secretion of the nerve impulse. |
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