The most important product of cells and what lies at the center of cellular activity is DNA (deoxyribonucleic acid). DNA contains the genetic instructions that govern the growth, development, functioning, and reproduction of all known living organisms. It serves as the blueprint for the synthesis of proteins, which are the workhorses of cellular activity. Proteins carry out various functions within cells, including enzyme activity, structural support, and cell signaling, making them central to cellular processes. So, DNA and its role in encoding genetic information are fundamental to cellular activity.