ATP stands for Adenosine Triphosphate.

Explanation:
- Adenosine Triphosphate (ATP) is an organic compound that serves as the main source of energy in living organisms.
- It is composed of three main components: adenosine, a ribose sugar molecule, and three phosphate groups.
- The structure of ATP consists of a nitrogenous base called adenine, a sugar molecule called ribose, and three phosphate groups.
- Adenine is a nitrogen-containing base that is also found in DNA and RNA.
- Ribose is a five-carbon sugar molecule that is similar to the sugar found in RNA.
- The three phosphate groups are the key to ATP's role as an energy carrier.
- The phosphate groups are negatively charged and are joined together by high-energy bonds.
- When one of these phosphate bonds is broken, energy is released, and ATP is converted into ADP (Adenosine Diphosphate) and an inorganic phosphate molecule (Pi).
- This process of breaking the phosphate bond and releasing energy is called hydrolysis.
- The energy released during ATP hydrolysis is used by cells to perform various functions, such as muscle contraction, active transport, and synthesis of macromolecules.
- ADP can be converted back into ATP through a process called phosphorylation, where a phosphate group is added back to ADP.
- This process occurs during cellular respiration and photosynthesis, where energy from glucose or light is used to regenerate ATP.
- ATP acts as a universal energy currency in living organisms, providing the energy needed for various cellular processes.
- It is constantly being synthesized and hydrolyzed in cells to maintain the energy balance required for life.
- Overall, ATP is a crucial molecule in cellular metabolism, as it stores and releases energy needed for cellular functions.