If a large molecule need to move against the concentration gradient the struc of an energy rich compound such as Adenosine tri phosphate or ATP is need to be used.
Explanation:
ATP provides energy to carry out the uphill transport of molecule across the plasma membrane by the helps of specific ion channel.Uphill transport is a type of membrane transport process in which a molecule is being transported against its concentration gradient that means the molecule is moving from low concentration region to high concentration region.
In general this type of transport is Thermodynamically unfavorable which is made favorable by the energy derived from the hydrolysis of ATP .
When a cell has energy available it can store small amounts of energy by adding a phosphate group to ADP molecules producing ATP molecules. The energy stored in ATP is released when ATP is converted to ADP and a phosphate group.
