The cell has many vital parts. The mitochondria are the power plants that provide energy (adenosine triphosphate) for cellular processes, and the ribosomes are factories that make all the proteins and enzymes required for cellular functioning. DNA is an indispensible component of cells, since it contains the genetic instructions for cellular functioning, protein synthesis, and heredity. If DNA is damaged, it can be fixed or replaced by DNA repair enzymes, but if DNA damage is not corrected, cell mutation or death can occur. Over time, this damage can accumulate and lead to diseases such as cancer, Alzheimer's, Parkinson's, and cardiovascular disease.