Q.25 Define uniport, symport and antiport. Do they require energy?

The biological membranes have many mechanism for movement of substances to and for. Some are active and some are passive. Specific membrane proteins are also involved for special types of transport mechanisms.
Uniport This is a membrane transport system by a integral membrane protein that is involved in facilitated diffusion. These channels get open in response to a stimulus for free flow of specific molecules in a specific direction. These transport molecule with solute gradient without energy expenditure.
Symport This involves the movement of two or more different molecules or ions, across the membrane in the same direction, with no energy expenditure.
Antiport also called exchanger, This integral membrane protein is involved in secondary active transport of two or more different molecules or ions across the membrane in opposite directions, without affecting the tansport of other molecules.