Question

How does ATP enable transport proteins to move?

Answer 1

Hint: Carrier protein that is transported across the lipid bilayer resembles an enzyme-substrate reaction. Energy from ATP causes a transport protein to change its size, binding the substrate on one side of the membrane.

Complete answer:
Active transport works independently of concentration gradients. It can produce ions across the membrane against a concentration of electrochemical gradients, from a region of low to high concentration. The carrier protein molecules utilize energy supplied by the cell to accumulate materials within or outside the cells. energy is required because the material is to be moved against its natural tendency to diffuse in the opposite direction. Active transport, thus, directly involves cell metabolism. It stops if the proteins are denatured or removed from the membrane.

The active transport depends on the ability of protein molecules to assume different forms by folding. The carrier protein has its cytoplasmic end binding site for ATP.ATP molecules are constantly colliding with the cytoplasmic face of the membrane. When an ATP molecule strikes its binding site on the carrier proteins, it attaches there. The release of energy causes a conformational change in the carrier protein.

This binding release the strain on the carrier protein segment and the molecules to be transported is carried through the hydrophilic channel in the carrier protein to the cytoplasmic surface of the membrane. The latter is, therefore, released into the cells. The phosphate group is also released at this time. Now the carrier protein regains its original conformation and becomes ready to bind a new ATP and restart the transport cycle. Thus during active transport, the carrier protein binds with ATP and uses its energy to pump the ions across the cell membrane in opposite directions

Note: Active transport is a vital process. If the cells are deprived of oxygen, active transport halts because ATP production is stopped. It is also affected by low temperatures and poisons. It helps in the transportation of materials, ions on a selective basis.