Concept 5 Review

ATP-powered Pumps

ATP-powered pumps (ATPases) couple the splitting, or hydrolysis, of ATP with the movement of ions across a membrane against a concentration gradient. ATP is hydrolyzed directly to ADP and inorganic phosphate, and the energy released is used to move one or more ions across the cell membrane. As much as 25% of a cell's ATP reserves may be spent in such ion transport. Examples include:

Step 1 Step 2 Step 3 Step 4 Step 5 Step 6 Step 7

Put It All Together Reset

If a proton gradient is established by the breakdown of other molecules, the transport process works in reverse to synthesize ATP from ADP and phosphate, using the energy of the proton gradient. To view animations summarizing operation of the ATP pump, click on the buttons, starting with "Step 1."