What is the primary role of mitochondria in muscle cells?

The primary role of mitochondria in muscle cells is energy production. Mitochondria are often referred to as the "powerhouses" of the cell because they are responsible for generating adenosine triphosphate (ATP), which is the primary energy carrier in all living organisms. During processes such as aerobic respiration, mitochondria convert nutrients derived from food into ATP, which is essential for muscle contraction and overall cellular function.

Muscle cells, especially those involved in endurance activities, contain a high density of mitochondria because they require significant amounts of energy to sustain prolonged activity. This abundance of mitochondria allows muscle fibers to efficiently produce energy to support their contractions during exercise.

In contrast, the other options do not directly align with the main function of mitochondria. For example, storage of proteins is a role associated with structures like the endoplasmic reticulum or Golgi apparatus, while oxygen transport is primarily the function of red blood cells through hemoglobin. Waste elimination involves cellular processes that do not specifically occur within the mitochondria themselves; rather, this function encompasses various cellular mechanisms across different organelles.