What directs all cellular activities contain long threadlike hereditary materials?

The structure that directs all cellular activities and contains long threadlike hereditary materials is DNA (deoxyribonucleic acid). DNA is organized into chromosomes and serves as the blueprint for an organism's genetic information, guiding processes such as growth, development, and reproduction. Through the processes of transcription and translation, DNA also dictates the synthesis of proteins, which are essential for various cellular functions.