the process by which a cell converts nutrients into energy or materials glucose 2. the conversion of nutrients into energy complete protein 3. the cell's main source of energy anabolism 4. the process by which the cells use nutrients to repair or build new tissues catabolism 5. the nutrient that is essential to cellular construction, reproduction, and maintenance metabolism 6. amino acids that cannot be manufactured by the body and must be derived from food sources protein 7. food source that contains all the essential amino acids essential amino acids 8. food sources that do not contain all the essential amino acids incomplete proteins