The structure in cells known as the powerhouse is the mitochondrion (plural: mitochondria). Mitochondria are organelles responsible for producing adenosine triphosphate (ATP), the primary energy currency of the cell, through a process called cellular respiration. This involves the conversion of nutrients, particularly glucose and oxygen, into energy. Mitochondria have their own DNA and are often referred to as the "powerhouses" because they generate energy required for various cellular processes, including muscle contraction, nerve impulse transmission, and overall metabolism, playing a crucial role in maintaining cell function.