The main carrier of genetic information in cells is deoxyribonucleic acid (DNA). DNA is a molecule composed of two strands that form a double helix structure, containing sequences known as genes, which encode the information necessary for building and maintaining organisms. DNA carries the genetic instructions through replication, ensuring that information is accurately passed from cell to cell during division. It plays a critical role in heredity and is fundamental in the processes of transcription and translation, which are essential for protein synthesis and cellular function.