Final answer:
Proteins contain essential amino acids necessary for metabolic functions, and they must be obtained from dietary sources as the body cannot synthesize all of them.
Step-by-step explanation:
The component that has amino acids essential for certain metabolic functions is proteins. Proteins are broken down into their component amino acids during digestion. The human body can synthesize only 11 of the 20 required amino acids; the rest, known as the essential amino acids, must be obtained from the diet. Unlike proteins, carbohydrates and fats do not contain amino acids, and vitamins are required in small quantities for different functions but also do not provide amino acids. The essential amino acids are crucial for various metabolic processes, including building new proteins and being involved in pathways that are critical to energy production and muscle repair.