What do cells primarily use for energy?

Cells primarily use carbohydrates for energy due to their structural composition and the ease with which they can be metabolized. Carbohydrates, such as glucose, are broken down through cellular respiration processes to release energy that can be utilized for various cellular functions. This energy is stored in the form of adenosine triphosphate (ATP), which is the primary energy currency of the cell.

The breakdown of carbohydrates involves glycolysis, the citric acid cycle, and oxidative phosphorylation, facilitating the conversion of glucose into ATP very efficiently. While fats and proteins can also serve as energy sources, they typically undergo more complex metabolic pathways and are utilized primarily when carbohydrate reserves are low. Nucleic acids, while critical in storing genetic information and protein synthesis, do not serve a direct energy role in the same way carbohydrates do. Thus, carbohydrates are the preferred and primary source of energy for cells.