In cell (whether it is plant or animal cell),there are many organelle present .Out of it ,mitochondria is also one of them .In mitochondria certain reactions takes place and as a result it produces energy in the form of ATP .That is the reason it is called as "Power house of cell "
The ATP has three phosphate groups ,once it is used a bit it gets converted to ADP (with 2 phosphate groups ),when used more it gets converted to AMP (one phosphate group )and when fully exhausted there is no phosphate group left and they occur in cytoplasm in form of phosphate ions .
