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Terms in this set (28)

87. Coenzymes and trace metals are known as Cofactors. Many, but not all, enzymes cannot work without cofactors. Don't be confused by the terms Coenzymes and Cofactors. A Coenzyme is one type of Cofactor. Many vitamins are necessary to make Coenzymes. Vitamins cannot be produced by the body and thus must be acquired in the diet. Trace metals are the other type of Cofactor. Calcium, Magnesium, Sodium, Iron, Zinc and many other trace metals must also be consumed in the food we eat. Cofactors, ie vitamins and trace metals, are necessary for normal cell functioning.. Because they are recycled, they are only needed in small amounts.
Coenzymes are necessary for energy metabolism: The coenzymes NAD+, Nicotinamide Adenine Dinucleotide, and FAD+, Flavin Adenine Dinucleotide, are critical to cell respiration and fatty acid metabolism. However, the body cannot make NAD+ without Vitamin B3 (Niacin) in the diet. Similarly, the body cannot make FAD+, without Vitamin B2 (Riboflavin) in the diet. NAD comes in two forms, charged (NAD+) and uncharged, bonded to hydrogen (NADH). Same with FAD, (FAD+ and FADH2). Where and how in the various biochemical reaction pathways does NAD+ become NADH? Give three examples. Where and how in the various biochemical reaction pathways does FAD+ become FADH2? These conversions of NAD+ and FAD+ coenzymes from charged states to NADH and FADH2 are easily reversible. This fact enables vitamins and coenzymes to be easily recycled in the body. Thus, we only need vitamins in small amounts. This raises the question about the usefulness of taking mega-doses of vitamins. Excess doses of water soluble vitamins like the B vitamins, niacin and riboflavin, and vitamin C only come out in the urine as the body excretes the amounts of vitamins it doesn't use. Vitamin B-12 is the exception. It is stored in the liver.