Final answer:
The mitochondria is the cell structure responsible for extracting energy from nutrients.
Step-by-step explanation:
The mitochondria is the cell structure responsible for extracting energy from nutrients. Mitochondria are often referred to as the "powerhouses" or "energy factories" of a cell because they produce adenosine triphosphate (ATP), which is the cell's main energy-carrying molecule. Through the process of cellular respiration, glucose oxidation releases a significant amount of free energy that is used to synthesize ATP.
This process is not exclusive to animals, as plants also convert nutrient energy into ATP, although they initially capture free energy directly from sunlight. Every cell uses ATP for various functions, like metabolizing imports, synthesizing new molecules, and transporting molecules. When ATP is synthesized (anabolism), it stores energy, which is later released (catabolism) to power cellular activities in a controlled manner.
It is more metabolically efficient for cells to extract energy from ATP rather than directly from the bonds of carbohydrates because ATP provides a readily controlled amount of energy that can be specifically allocated for different cellular needs, minimizing the risk of damage from uncontrolled release of energy.