What is ATP? Write its full form.

ATP stands for Adenosine Triphosphate, a nucleotide that functions as the universal energy currency of cells. This molecule consists of three components: adenine (a nitrogen-containing base), ribose (a five-carbon sugar), and three phosphate groups linked in a chain. The energy in ATP is stored in the high-energy bonds between the phosphate groups, particularly the bond connecting the second and third phosphate. When the cell requires energy for any process, ATP is hydrolyzed (broken down) into ADP (adenosine diphosphate) and an inorganic phosphate group, releasing approximately 7.3 kcal/mol of energy that can be immediately used for cellular work.

ATP powers virtually every energy-requiring process in living cells—muscle contraction, nerve impulse transmission, active transport of molecules across membranes, protein synthesis, DNA replication, and cell division all depend on ATP. Cells continuously recycle ATP; the ADP and phosphate produced when ATP releases energy are recombined using energy from cellular respiration (in mitochondria) or photosynthesis (in chloroplasts) to regenerate ATP. An average human body recycles its own body weight in ATP daily, demonstrating the molecule's critical role. This rapid turnover system allows cells to store energy in a readily accessible form rather than maintaining large energy reserves, making ATP an efficient solution to the constant energy demands of life. The mitochondria's role in producing ATP explains why they are called powerhouses of the cell.