ATP powers transport, specifically in active transport, by providing the energy required to move molecules against their concentration gradient. This contrasts with passive transport, which does not require energy input.
Here's a breakdown of the process:
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ATP and Active Transport: Active transport mechanisms require energy because they move substances from an area of lower concentration to an area of higher concentration. This is "uphill" and requires work. ATP (adenosine triphosphate) is the cell's primary energy currency.
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ATP Hydrolysis: The energy is released when ATP undergoes hydrolysis, breaking one of its phosphate bonds. This reaction converts ATP into ADP (adenosine diphosphate) and inorganic phosphate (Pi). The energy released during this process is harnessed by transport proteins.
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Transport Proteins: Special transport proteins, often called "pumps," are integral membrane proteins. These proteins bind both the molecule to be transported and ATP.
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Coupling Energy to Transport: The transport protein utilizes the energy released from ATP hydrolysis to change its shape, allowing it to "grab" the molecule on one side of the membrane, move it across, and release it on the other side where the concentration is higher.
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The Cycle Repeats: After releasing the molecule, the protein reverts to its original shape, ready to bind another molecule and repeat the process, provided there is sufficient ATP.
In summary: ATP powers transport work by being hydrolyzed (broken down), releasing energy that transport proteins use to move molecules against their concentration gradients across a cell membrane.
