Question

How are the proteins used for active transport different from those used for facilitated diffusion?

The proteins for facilitated diffusion must attach to a carbohydrate to work.

The proteins used in facilitated diffusion create larger openings in the cell membrane.

The proteins involved in active transport must be powered by ATP to work.

The proteins that carry out active transport move only the largest molecules.

Answer 1

The proteins involved in active transport must be powered by ATP.

Proteins involved in facilitated diffusion often form membrane-spanning channels or carriers that permit entry/exit of larger or charged molecules that would be otherwise unable to pass through the lipid bilayer. These permit movement of compounds along their concentration gradient. Such proteins are also called uniporters.

In primary active transport, transporter proteins use ATP directly to move a compound against its concentration gradient. In secondary active transport, a transporter protein uses the energy derived from one compound moving down its concentration gradient to simultaneously move another compound against its concentration gradient. The gradient of the first compound is established by primary active transport, so secondary active transport also uses ATP, though indirectly. The transporters are called symporters or antiporters depending on whether the compounds it transports move across the membrane in the same or opposite direction.