1. Storing genetic information: DNA acts as a blueprint for building and maintaining an organism. It contains the instructions for making proteins, which carry out a vast array of functions in the body. These instructions are encoded in the sequence of nucleotides within the DNA molecule.

2. Passing on genetic information: DNA is replicated during cell division, ensuring that each new cell receives a complete copy of the organism's genetic information. This allows for the transmission of traits from one generation to the next.

3. Controlling gene expression: DNA does not directly control all cellular processes. Instead, specific portions of the DNA sequence (genes) are transcribed into RNA molecules, which then serve as templates for protein synthesis. This process of gene expression is carefully regulated, ensuring that the right proteins are produced at the right time and place.