James C. answered • 09/12/22
Science Tutor in the Inland Empire
The cell uses ATP as an energy source to carry out biochemical reactions that are essential to life. The conversion of ATP to ADP is a thermodynamically highly favorable process. The cell couples this thermodynamically highly favorable reaction with other important biochemical reactions so that they may proceed.
ADP is like ATP, but ATP has three phosphate groups, whereas ADP has only two phosphate groups. ADP can get converted into ATP through reactions in glycolysis and through a different process called oxidative phosphorylation.
Whenever the ADP concentration in the cell is high, the ATP concentration in the cell is low. This means that the cell is lacking in energy. Conversely, when the ATP concentration in the cell is high, the ADP concentration is low. This means that the cell is rich in energy.
ADP can bind to an enzyme called Phosphofructokinase (PFK). This enzyme plays a key role in glycolysis. When ADP binds PFK, it "activates" it. In other words, ADP can increase the activity of PFK in the cell, which would increase the rate of glycolysis. This means that the cell would be producing more energy for itself in the form of ATP. This makes sense, since if the concentration of ADP in the cell is high, the cell is low in energy. The higher the concentration of ADP in the cell, the more likely it is to bind to PFK and increase the rate of glycolysis. When glycolysis is running at a high rate, the cell can make more energy for itself in the form of ATP.
