Problem: Evaluate the six major classes of nutrients and their purpose. Discuss the importance of the three macronutrients: carbohydrates, protein and fat. What is the difference between structural and non-structural carbohydrates? What are the essential amino acids in animals? What are the essential fatty acids in animals? What is the difference between essential and non-essential nutrients? Provide 2-4 examples of common dietary sources for each nutrient (e.g., corn is a common carbohydrate source). Need Assignment Help?