What is the primary role of mitochondria in the cell?

Mitochondria are often referred to as the "powerhouses" of the cell because their primary function is to produce adenosine triphosphate (ATP), which is the main energy currency of the cell. This process occurs through cellular respiration, where glucose and oxygen are used to generate ATP, along with water and carbon dioxide as by-products. The efficiency of ATP production in mitochondria is crucial for various cellular functions, including muscle contraction, biosynthesis, and maintaining ion gradients.

In contrast to the correct answer, the other options refer to different cellular processes. The packaging of proteins is primarily performed by the Golgi apparatus, while nutrient storage is often associated with vacuoles or cytoplasmic structures. Ribosome assembly occurs in the nucleolus of the nucleus, not in mitochondria. Understanding the specific roles of these organelles provides insight into how cells function and maintain energy balance.