In order to maintain homeostasis, human cells must have a higher concentration of sodium ions outside the cell than inside the cell. In addition, the concentration of potassium ions must be higher inside the cell than outside the cell. Which of the following forms of cellular transportation helps human cells maintain a relatively constant sodium and potassium concentration?
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The form of cellular transportation that helps human cells maintain a relatively constant sodium and potassium concentration is called the sodium-potassium pump.
To understand how the sodium-potassium pump works, we need to look at the process of active transport. Active transport is a type of cellular transportation that requires energy and moves substances against their concentration gradient.
The sodium-potassium pump is a specialized protein found in the cell membrane of human cells. It actively transports sodium ions (Na+) out of the cell and potassium ions (K+) into the cell. This process occurs simultaneously, meaning three sodium ions are transported out for every two potassium ions transported in.
Here's a step-by-step explanation of how the sodium-potassium pump works:
1. The pump is activated by the presence of sodium ions inside the cell.
2. The pump binds three sodium ions from the cytoplasm, stimulating ATPase activity, which fuels the pump.
3. ATP (adenosine triphosphate) is hydrolyzed by the pump, providing the necessary energy.
4. As ATP is broken down, a phosphate group is attached to the pump, causing it to change its conformation.
5. This conformational change allows the pump to release the three sodium ions outside the cell.
6. At the same time, two potassium ions from outside the cell bind to the pump.
7. The binding of the potassium ions triggers the release of the phosphate group from the pump, restoring its original conformation.
8. As a result, the potassium ions are transported into the cell.
9. The process continues with three sodium ions binding and being transported out and two potassium ions binding and being transported in.
By using ATP energy, the sodium-potassium pump maintains the necessary concentration gradients for sodium and potassium ions across the cell membrane. This is vital for numerous cellular processes, including nerve cell function and muscle contraction.
So, in summary, the sodium-potassium pump is the form of cellular transportation that helps human cells maintain a relatively constant sodium and potassium concentration by actively pumping sodium ions out of the cell and potassium ions into the cell.