Carbohydrates are molecules that contain Carbon, Hydrogen, and Oxygen. The most basic sugar-carbohydrate is the monosaccharide. Carbohydrate molecules are categorized by the number of carbons present in the molecule.
Glucose, the most common monosaccharide has six carbons per molecule, which is called a hexose. Carbohydrates also have a 2:1 hydrogen to oxygen ratio. This aids in the condensation and hydrolysis reaction. A condensation reaction occurs when two monosaccharide join by the removal of H2O. During condensation synthesis one monosaccharide losses an OH and the other losses a H. As a result the two disaccharide with a by-product of a free H2O. When three or more monosaccharides or monomer are involved in condensation synthesis a polymer or polysaccharide is formed with a byproduct of water. Starch and Glycogen are two common chain polymers.
Just as the removal of water joins carbohydrates together via condensation synthesis, hydrolysis is the reaction using water to break apart Di and polysaccharide. A Di-saccharide is bound by sharing oxygen with one hydrogen on each opposing side. When H2O is re-introduced via hydrolysis the two monomers in the disaccharide no longer need to share one H2O, and as a result the opposing sides.
We need carbohydrates because carbohydrates are the macronutrient that we need in the largest amount. According to the Dietary Reference Intakes published by the USDA, 45%-65% of calories should come from carbohydrates. We need this amount of carbohydrate because: Carbohydrates are bodyâ€™s main source of fuel. Carbohydrates are easily used by the body for energy. All of the tissues and cells in our body can use glucose for energy. Carbohydrates are needed for the central nervous system, the kidneys, the brain, and the muscles to function properly. Carbohydrates can be stored in the muscles and liver and later used for energy. Carbohydrates are important in intestinal health and waste elimination.
Carbohydrates are mainly found in starchy foods like grain and potatoes, fruits, milk, and yogurt. Other foods like vegetables, beans, nuts, seeds, and cottage cheese contain carbohydrates, but in lesser amounts.
Fiber refers to certain types of carbohydrates that our body cannot digest. These carbohydrates pass through the intestinal tract intact and help to move waste out of the body. Diets that are low in fiber have been shown to cause problems such as constipation and hemorrhoids and to increase the risk for certain types of cancers such as colon cancer. Diets high in fibers; however, have been shown to decrease risks for hearts disease, obesity, and they help lower cholesterol. Foods high in fiber include fruits, vegetables, and whole grain products.
Proteins are large macromolecules which consist of hydrogen, carbon, and oxygen. Proteins are polymeric chains that are built from monomers known as amino acids. Proteins have a major function in a living organism, for example, the replication of DNA catalyzing metabolic reactions; stimulus response and also transporting molecules from one place to another. There are 20 different types of amino acids which synthesize protein, however the function and different properties of each type of protein is due to the precise sequence and structure of the amino acids present.
Each amino acid consists of a central carbon atom(C), which is attached to a hydrogen atom (H), an amino group, a carboxyl group and also a unique side chain or R group. Amino acids are linked linearly via covalent peptides bond, short chain amino acids are known as peptides whereas long chain formations of amino acids are called polypeptides, where the peptide bond is formed between the carboxyl group of one amino acid and the amino group on the neighboring amino acid. This reaction occurs as a condensation reaction where there is a removal of a hydrogen atom from the amino group of one amino acid and the removal of a OH group from the carboxyl acid from another amino acid forming a water molecule.
We need protein because according to the Dietary Reference Intakes published by the USDA 10%-35% of calories should come from protein. Most Americans get plenty of protein, and easily meet this need by consuming a balanced diet.
We need protein for: growth especially important for children, teens, and pregnant women, tissue repair, immune function, making essential hormones and enzymes, energy when carbohydrate is not available, preserving lean muscle mass.
Protein is found in meats, poultry, fish, and meat substitutes, cheese, milk, nuts, legumes, and in smaller quantities in starchy foods and vegetables.
When we eat these types of foods, our body breaks down the protein that they contain into amino acids. Some amino acids are essential which means that we need to get them from our diet, and others are nonessential which means that our body can make them. Protein that comes from animal sources contains all of the essential amino acids that we need. Plant sources of protein, on the other hand, do not contain all of the essential amino acids.