Final answer:
Antiporters and symporters are transport proteins that facilitate the movement of one ion or molecule against its concentration gradient while simultaneously moving another ion or molecule down its gradient, crucial for active transport mechanisms in cells.
Step-by-step explanation:
Transport proteins that couple the movement of one ion or molecule against its concentration gradient with the movement of another molecule or ion down its concentration gradient are known as c) antiporters or symporters.
These transporter proteins are essential for active transport, as they facilitate the movement of substances across cell membranes.
A uniporter carries one specific ion or molecule, a symporter carries two different ions or molecules in the same direction, and an antiporter carries two different ions or molecules but in opposite directions. All these transporters are also known to move small, uncharged organic molecules such as glucose.