The element crucial for the reproduction of cells is phosphorus, particularly in the form of nucleotides found in nucleic acids such as DNA and RNA. Phosphorus is a key component of the backbone structure of these molecules, helping to store and transmit genetic information. Additionally, phosphorus is vital for cellular energy transfer, as it is present in adenosine triphosphate (ATP), the primary energy carrier within cells. This element plays a significant role in various biological processes, including metabolism, cell signaling, and growth.