What is the primary function of mitochondria in cells?

Mitochondria are often referred to as the "powerhouses" of the cell due to their primary role in generating adenosine triphosphate (ATP), which is the main energy currency of the cell. This process occurs through cellular respiration, a series of metabolic reactions that convert energy stored in nutrients into ATP.

During cellular respiration, glucose and other substrates are broken down in a series of steps that occur primarily in the mitochondria. This process involves glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation, where the energy from electron transport is used to synthesize ATP. The ability to efficiently produce ATP allows cells to perform a wide range of functions, supporting metabolism, growth, and maintenance.

Each of the other choices is related to functions that are not primarily associated with mitochondria: while protein synthesis primarily occurs in ribosomes, storage of genetic information is a role of the nucleus, and regulation of cell division is a function more closely associated with the cell cycle machinery and mechanisms within the nucleus. This distinguishes the primary function of mitochondria as energy production through ATP generation, making the correct answer clear.