vitamin B12
The definitions used in this glossary of terminology either have been provided by the authors of the articles, or have been extracted wholly or in part, or paraphrased from the following sources: The American Medical Association Encyclopedia of Medicine, Charles B. Clayman, MD, Medical Editor, Random House, New York, 1989; Biotechnology from A to Z, 2d Edition, William Bains, Oxford University Press, New York, New York, 2002; A Dictionary of Genetics, 6th Edition, Robert C. King and William D. Stansfield, Oxford University Press, New York, New York, 2002; Dorland's Illustrated Medical Dictionary, 29th and 30th Editions, W. B. Saunders Company, Philadelphia, 2000, 2003; Genes VII, Benjamin Lewin, Oxford University Press, New York, New York, 2000; The Gale Encyclopedia of Genetic Disorders, Volumes I and II, Stacey L. Blachford, Ed., Thomson Learning, New York, New York, 2002; The Merriam-Webster Dictionary, Merriam-Webster, Inc., Springfield, Massachusetts, 1997; Molecular Biology of the Cell, 3rd Edition, Bruce Alberts, et al., Garland Publishing, 1994; The Random House Dictionary of the English Language, Unabridged Edition, 1966; Webster's Ninth New Collegiate Dictionary, 1991.
DEFINITION:
- vitamin B12
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Cyanocobalamin by chemical definition, but generally any substituted cobalamin (definition 2) derivative with similar biological activity; it is a water-soluble hematopoietic vitamin occurring in meats and animal products. To be absorbed by the intestine, it must combine with intrinsic factor, and its metabolism is interconnected with that of folic acid. The vitamin is necessary for the growth and replication of all body cells and the functioning of the nervous system, being required for purine and pyrimidine (and hence DNA, protein, and nucleoprotein) synthesis, methylation reactions, hematopoiesis, and myelin synthesis; at least some of these effects are mediated through its role in folic acid metabolism. Deficiency of the vitamin causes pernicious anemia and other forms of megaloblastic anemia, and neurologic lesions.
Used in 10 Term definitions
Used in 10 Term definitions