What is the function of mitochondria in a cell?

Mitochondria are often referred to as the "powerhouses" of the cell because their primary function is to produce energy in the form of adenosine triphosphate (ATP). Through a process known as cellular respiration, mitochondria convert nutrients from food into usable energy. This process involves several stages, including glycolysis, the citric acid cycle (Krebs cycle), and the electron transport chain.

In addition to energy production, mitochondria play important roles in other cellular processes, such as regulating metabolism and apoptosis (programmed cell death), making them essential for maintaining cellular health and function. The energy generated by mitochondria supports various activities within the cell, including growth, reproduction, and movement.

While other options relate to important cellular functions, they do not pertain to what mitochondria do. For example, sorting and packaging proteins is the role of the endoplasmic reticulum and Golgi apparatus, the digestion of old organelles is primarily performed by lysosomes, and cell division involves structures like centrioles and the mitotic spindle, not mitochondria.