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Description: There are three active forms of vitamin A: all-trans-retinol, -retinal, and –retinoic acid. Collectively, these are referred to as retinoids. The vitamin can be either consumed in the diet as esterified retinol, or biosynthesized from b-carotene, a plant isoprenoid especially abundant in carrots. b-carotene is cleaved in the intestine by a monooxygenase to form two molecules of all-trans-retinal (retinaldehyde), which are then reduced to retinol. All-trans-retinol is the form which circulates in the blood and which has the highest biological activity. Picture Stats: Views: 270 Filesize: 67.84kB Height: 750 Width: 340 Source: https://biology-forums.com/index.php?action=gallery;sa=view;id=34716 |