Like carbohydrates and
fats, proteins contain carbon, hydrogen, and oxygen, but in different
proportions. In addition, and most important, they are the only nutrient group
that contains nitrogen, and some contain
sulfur. Figure 6-1 is an example of an amino acid with a nitrogen (N) molecule.
Proteins are composed
of chemical compounds called amino acids (Figure 6-2). Amino
acids are sometimes called the building blocks of protein because they are
combined to form the thousands of proteins in the human body. Heredity
determines the specific types of proteins within each person.