Adenosine triphosphate (atp) is a molecule that is often used to transfer chemical energy within cells for metabolism. in addition, it is used for many other cellular processes, including biosynthetic reactions and cell division. atp is typically synthesized and destroyed locally, as metabolic processes that use atp as an energy source generally convert it back into its precursor molecules. because of this, atp is continuously recycled in organisms. for example, at any moment the human body contains approximately 250 grams of atp, but over the course of a day creates approximately its own weight in this molecule. during high-intensity exercise such as sprinting or lifting a very heavy weight, energy is provided to cells by the phosphagen system (or atp-pc system), which only works for a few seconds. if the diffusion constant of atp is 3 ×10−10 m2 s-1, how far could this molecule diffuse in 4.4 seconds