The minerals are inorganic ions. When one looks at the periodic table with all the known elements, we find that all or almost all are required by living organisms. This is true for both simple and complex life. Some of the minerals such as calcium and phosphate are used in larger amounts by organisms when they are used to build structures such as bones and shells (exo and endoskeletons). Also, large amounts are needed in body fluids for osmotic balance with the cells of the organism. Another very important function of minerals is to act as cofactors of enzymes. These are essential for all living systems and for this function only small amounts are necessary.

ORGANIC BIOMOLECULES

All of the other biomolecules contain carbon and as a consequence are called organic molecules. They also contain atoms of nitrogen, hydrogen, carbon, oxygen and some contain sulfate or phosphate as an integral part of the molecules. The middle-sized molecules which are between 100 and 1000 daltons are the subunits of the macromolecules, the vitamins, and "metabolites" or "intermediates." This latter group are molecules which are being degraded or synthesized. The subunits of proteins are the 20 different amino acids, the subunits of nucleic acids are the five different nucleotides (ATCG), the subunits of many lipids are a variety of fatty acids. The subunits of carbohydrates or polysaccharides are called monosaccharides or sugars.

VITAMINS

Vitamins are also small organic molecules but they are not subunits of any macromolecule. Their function is to work with enzymes and other proteins in our body and they are converted to molecules called coenzymes. Folate or folic acid is a vitamin that we know is important in preventing birth defects and in protecting us from heart disease. Vitamin D deficiency causes rickets in children and softening of the bones and osteoporosis in adults. Vitamin A and E are called antioxidants and protect the cells from "free radicals" which can cause gene mutations and therefore cancer. (Cancer is caused by mutations in our body cells.) Vitamin K helps in blood clotting. A rat poison, warfarin (Wisconsin Alumni Research Foundation patented it) is an analog of Vitamin K meaning that it looks chemically like Vitamin K but does not function like Vitamin K. Rats get injured frequently and if they have ingested warfarin, they will die because of internal hemorrhaging. It is an effective and efficient poison because other rats that eat the dead rat will also get a dose of warfarin and die. Vitamin A which is synthesized from beta carotene is converted to retinene and works with a protein called opsin. Together they form rhodopsin, a very important molecule in vision. The RDA (recommended daily amount) is a minimal dose below which you will have symptoms associated with a deficiency of that vitamin. Long ago, sailors did not get enough Vitamin C because they did not have fresh fruit and vegetable on board. They got scurvy marked by anemia, spongy gums, a tendency to hemorrhages in the mouth and a hardening of the leg muscles. Vitamins do not have the exact same function in all organisms as they do in us. Many agree that it is a good idea to supplement your diet with vitamins and minerals to be certain you have what you need. Each of us is biochemically unique in our requirements for vitamins.

CARBOHYDRATES OR POLYSACCHARIDES (AND SUGARS)

The term carbohydrate is often used very loosely to mean both simple sugars and more complex sequences of simple sugars. The term refers to the fact that carbohydrates all contain carbon atoms which are "hydrated".........C _n(H₂O)_n.....where "n" refers to the fact that the number can vary. Sugars (monosaccharides) usually have five or six carbons. The term, "simple carbohydrate" means one or a few monosaccharides and "complex carbohydrate," means larger sequences of monosaccharides or what biochemists call polysaccharides. Labels on canned and other foods will often refer to the "carbohydrate" content and include the amount of sugar in the product as well as complex carbohydrates. Many of the simple sugars or monosaccharides contain a six carbons (glucose, fructose, galactose). The sugars that are part of nucleotides are five carbon sugars (ribose and deoxyribose). Carbohydrates and sugars usually have names ending in "ose." The sugar on your table is sucrose which is a disaccharide composed of one molecule of glucose and one molecule of fructose. Glucose is not very sweet but fructose is.

Polysaccharides include glycogen, plant starch (amylose), cellulose, and chiton (a constituent of the shells of arthropods). They are all homopolymers meaning they are all made of only one sugar repeated over and over. The first three are composed exclusively of glucose but some have branches (glycogen) and some do not (plant starch and cellulose). Cellulose is the primary component of plant cell walls. The glucose units of which it is composed are linked together by a slightly different bond which cannot be broken down by the enzymes found in animals although some microorganisms have enzymes that can digest cellulose. Therefore, herbivores must have cultures of these microorganisms somewhere in their digestive tract. Our salivary gland produces amylase, an enzyme which breaks down amylose (plant starch). (Enzyme names end in "ase.") If you eat a soda cracker and hold it in your mouth awhile it will begin to taste sweet because you are breaking the bonds of the carbohydrate into its component glucose units which have a sweet taste.

Chitin is also a homopolymer but is made of repeating subunits of N-acetyl-glucosamine, a derivative of glucose which has an amino group (containing nitrogen). We also have some extracellular polysaccharides in our joints called glycosaminoglycans (GAGs). These act as "springs" in our joints. Today chondroitin sulfate (a GAG) and glucosamine (a monosaccharide constituent) are sold in health food stores to prevent or ameliorate arthritis. Some lethal genetic disorders are due to the lack of the appropriate enzyme needed to recycle these GAGs which then accumulate in the joints and in openings in bone.

Oligo means few. (Poly means many.) Oligosaccharides are a few sugars attached to one another. They are often attached to proteins and lipids found in the cell membrane. The protein is then called a glycoprotein and the lipid is called a glycolipid. They are signals, sort of like "zip codes." They are recognition sites for molecules (hormones), foreign organisms (bacteria, viruses) and other cells. The A, B, O, AB blood types are due to glycoproteins and glycolipids on our cell membranes. The genes for the blood types code for enzymes which synthesize the oligosaccharide portion of a glycoprotein and glycolipid in the cell membrane.

LIPIDS: FATS AND STEROLS

The "saponifiable lipids" contain fatty acids. Saponifiable refers to the making of soap from animal fats using lye (sodium hydroxide) to break down the lipids to their component parts. The sodium salts of the fatty acids were soap. Triglycerides are three fatty acids attached to a glycerol (glycerine) molecule. Fatty acids are long carbon chains with hydrogen attached to the carbon but no oxygen (as you see in sugars). They do not form rings. Triglycerides are stored for energy and metabolic water (as in the camel's hump). Other fatty acids attached to fancier molecules than glycerol (ones with a positive and/or negative charged group on them) have a polar (hydrophilic) head end and a non-polar (hydrophobic) tail where the fatty acids are. These lipids form a lipid bilayer and are an integral part of all cell membranes. The outer charged part of the molecules in the bilayer can interact with the extracellular fluid on one side and with the intracellular fluid on the other side of the membrane while the inner uncharged part of the molecule makes a seal so that the intra and extracellular fluid areas cannot mix easily.

The non-saponifiable lipids are the sterols. They do not contain fatty acids. Instead they are all built on a similar carbon ring structure that resembles a section of "chicken wire." Cholesterol is a sterol which is very important in our cell membrane. It keeps it flexible. There are many hormones built on the same plan: estrogen, progesterone, testosterone, cortisol. (Common endings for sterols are "ol" and "one.")

Fatty acids are subunits of many lipids. Fatty acids consist of long chains of carbon and hydrogen. The number of carbons in the chain varies but is always a multiple of two. Fatty acids are "saturated" if all of the carbons in the chain have the maximum numbers of hydrogens attached (two per carbon) and as "unsaturated" when some carbons have only one hydrogen attached. Carbon atoms that only have one hydrogen form a "double bond" with the next carbon. This put a kink in the chain and cell membranes with more unsaturated fatty acids are more fluid than those with less. Deep sea fish that live in very cold waters put unsaturated fatty acids in their membrane lipids as a kind of "antifreeze." A major function of lipids is to form the cell membrane. The lipids in the cell membrane contain fatty acids which are attached to another molecule which has charged groups on it. The part of the lipid which is charged (polar end) dissolves in the extracellular or intracellular fluid while the fatty acid chains form the inner portion of the membrane and exclude water. Some fatty acids are attached to glycerol and the resulting molecules are called triglycerides. These neutral fats function to store energy. Fats also provide insulation for the body. Not all lipids contain fatty acids. Another group of lipids are the sterols. They contain carbons in rings and not in chains. Cholesterol is an important sterol. It also functions in the cell membrane and provides flexibility to the membrane. Other sterols are the hormones, testosterone, estrogen, progesterone and cortisone. Because these hormones are fat soluble, they can enter the cell easily and do not require special receptors as the protein hormones do.

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