Before we go any further on metabolism, we should learn what Purines are. They come from the food that we ingest. Who thought food could have such a fancy name? Purines, by definition are "A double-ringed, crystalline organic base, C5H4N4, not known to occur naturally, from which is derived the nitrogen bases adenine and guanine, as well as uric acid as a metabolic end product."
Now, back to metabolism. Metabolism occurs in living organisms, to sustain life, and/or to synthesize. In humans, it does both. We require such things as nutrients to sustain our being, and metabolism takes these vitamins out of purines. without a metabolism, we would eat and fill up once, never have a bowel movement, and slowly decay from vitamin deficiency.
And there you have it! For you out there who you they know it all, I threw in some big words, and for you out there who don't know the first thing about metabolism, there you go! You can aquire more information on metabolism or purines from books, internet sources, or you doctor.
