Question

Assume you consume in excess of 50 kg of ATP/day. Are you able to meet this high energy demand by storing large quantities of ATP within your cells?

Answer 1

Adenosine triphosphate or ATP is used for most of the energy requiring cellular reactions. This ATP needs to be generated at a rate complementary to ATP demand. In the cells, energy is provided by the oxidation of carbohydrates, lipids, and proteins and is used for the synthesis of macromolecules, muscle contraction ion transport etc. The oxidation process results in free energy production which is stored in molecules such as ATP and ADP which has high energy bonds within its molecules. ATP performs cellular work using ATP by energy coupling through phosphorylation. Any high energy demands needs the breakdown of ATP to release energy. So we may think that the large amount of storage of ATP or extra ATP consumption will be beneficial for any extra demand of energy. This is not true. In a cell, the total quantity of energy that is stored is very small and ATP and ADP is stored in equilibrium. If large amount of energy is stored in the cell it can change this equilibrium state as ATP is very unstable. This is stated in Le Chatelier's principle that says any change in pressure, temperature or concentration is changed in an equilibrium state it can shift its state of equilibrium. So this results in huge break down of ATP and destruction of cell may occur. For any extra demand of energy the cells relies on other mechanisms. The molecules like glycogen, triacylglycerols etc. breaks down and metabolism increases to meet ATP demand. The energy stored in cells do not change much during any intense exercises, but there are mechanisms for the resynthesis of ATP such as glycolytic systems, mitochondrial respiration and phosphagen system to meet the ATP demands.Also ATP is a substrate for RNA polymerase, so if ATP is present in higher levels than other RNA substrates Uridine-5'-triphosphate (UTP) or Guanosine-5'-triphosphate(GTP) it may cause errors in transcription.