What is the main role of DNA within a cell?

DNA plays a crucial role in the cell primarily as the storage medium for genetic information. This genetic information serves as the blueprint for synthesizing proteins, which are essential for various cellular functions and processes. The sequences of nucleotides in DNA encode the instructions necessary for the production of proteins through the processes of transcription and translation.

In addition to protein synthesis, DNA also plays a regulatory role within the cell, helping to control when and how genes are expressed based on the cell's needs and environmental signals. This regulation is vital for maintaining proper cellular function and responding to changes in the environment.

Other options describe different functions that are not the primary role of DNA. For instance, while DNA is involved indirectly in processes such as cell division (as it must be replicated before a cell divides), its main role is in storing and providing the instructions for genetic expression. Similarly, DNA does not provide energy for cellular functions; energy is primarily derived from molecules such as ATP. Lastly, DNA is not involved in forming cellular membranes; that function is performed by lipids and proteins that make up the membrane structure. Overall, the primary function of DNA is its role in storing and regulating genetic information critical for life.