Question

What is Facilitated diffusion? How is symport transport different from antiport transport?

Answer 1

Hint: Transport in membranes deals with the movement of materials across the membranes of cells. Transport is a necessity for the cells for the uptake of nutrients. This activity along with the movement of ions and other molecules is offered by proteins and protein complexes, which are highly specific for the compounds they move. This selective movement and ions’ lower permeability across the lipid bilayer aid in maintaining the osmotic balance of the cell.

Complete answer
Other names for the facilitated diffusion are facilitated transport and passive-mediated transport. It is opposed to active transport and is a process of spontaneous passive transport of ions or molecules across a biological membrane through specific transmembrane integral proteins. It occurs when the driving factor for the movement is diffusion.
The driving force for facilitated diffusion is concentration. The materials move from a side of higher concentration to a side of lower concentration and by the end of the process, the concentration of materials on both sides are equal. Red blood cells acquiring glucose is an example of facilitated diffusion.
Fig.: Symport, Antiport and Uniport modes of Transport

Symport Transport	Antiport Transport
A symporter is an integral membrane protein. It is involved in the transport of various kinds of molecules across the cell membrane. As two molecules travel in the same direction in relation to each other, the transporter is called a symporter	An antiporter is also an integral membrane protein, but two molecules travel in opposite directions in relation to each other.
Sodium sugar pump and hydrogen sugar pump are involved in the symport transport system.	Sodium potassium pump and sodium-calcium exchanger are involved in the anti-port transport system.

Note:
Both symporter and antiporter act as cotransporters and are a type of secondary active transport. Uniport is an integral membrane protein, where transport of only one molecule is involved. Carrier proteins are involved in primary active transport, whereas transmembrane proteins are involved in secondary active transport. The antiporter transport substrates in two directions, whereas both uniporter and symporter transport molecules in a single direction.