Dietary Reference Intake - Essay Example

Macronutrients
As well, macronutrients are played significant roles in the structure, physiology, and immunity of the human body.
Carbohydrates, commonly known as saccharides or sugars, have an empirical formula Cx(H20)y where the number of carbon may match the number of H2O molecules or not. As shown by the molecular structure C6H12O6, glucose is an example of a carbohydrate having equal numbers of carbon and water molecules. On the other hand, the carbohydrate backbone of DNA deoxyribose is an example of unequal numbers of carbon and water, as shown by the formula C5H10O4.

Carbohydrates perform a wide variety of functions in the human body. These macronutrients may function as storage for energy in the form of starch and glycogen. They can also function like cellulose and chitin as structurally significant molecules. As mentioned earlier, carbohydrates like deoxyribose and ribose play key roles in heredity as the backbone of the genetic molecule DNA and RNA. Physiologically, ribose is also an important component in coenzymes like flavin adenine dinucleotide (FAD), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide (NAD).

Secondly, proteins are another class of organic compounds that fall under the macronutrient category. Structurally, proteins are typically one or more polypeptide chains linked together that fold into different forms depending on their biological function. A polypeptide, for example, is an amino acid polymer chain linked together by peptide bonds.

Depending on their function, proteins may fold into one of two configurations, globular or fibrous, and in this folding, they add on non-peptide groups called cofactors or prosthetic groups depending on their biological function (i.e. the Heme group in Hemoglobin). Humans tend to require a great number of proteins because, like carbohydrates, macronutrient plays different roles in almost all cellular processes. The most common notion people have of proteins is their role in mechanical and structural support. This involves the actin and myosin found in the muscles as well as the proteins which build the cytoskeleton, the structure that supports and shapes the cells. Some proteins also function as catalytic enzymes which facilitate physiological reactions, specifically in metabolism. As mentioned earlier proteins, play vital roles in almost all cellular processes, like signaling, adhesion, immune responses, and reproduction.

Unlike the macronutrients carbohydrates and proteins, which collectively possess a specific characteristic, chemical structure, or form that categorizes all the members of their group, the third class of lipids, is a rather broad and varied category. Organic compounds that are soluble in organic solvents, insoluble in water, and cannot be classified elsewhere are categorized into lipids. Lipids are further classified into such subgroups as oils, waxes, triglycerides, vitamins, and steroids. Oils are described as compounds that are greasy and liquid at room temperature while waxes are lipids that are solid at room temperature.