Conserved non-coding sequence degenerate sequences with no biological function. An example of a pseudogene is the gene for L-gulonolactone oxidase, a liver enzyme necessary for biosynthesis of L-ascorbic acid (vitamin C) in most birds and mammals, but which is mutated in the haplorrhini suborder of primates, including humans which require ascorbic acid or ascorbate from food. The remains of this non-functional gene with many mutations is still present in the genomes of guinea pigs and humans. Ultraconserved regions (UCRs) are regions over 200 bp in length with 100% identity across species. These unique sequences are mostly found in noncoding regions. It is still
Vitamin C and also regenerator of other antioxidants. Plants use multiple pathways to synthesize vitamin C. The major pathway starts with glucose, fructose or mannose (all simple sugars) and proceeds to L-galactose, L-galactonolactone and ascorbic acid. There is feedback regulation in place, in that the presence of ascorbic acid inhibits enzymes in the synthesis pathway. This process follows a diurnal rhythm, so that enzyme expression peaks in the morning to support biosynthesis later on when mid-day sunlight intensity demands high ascorbic acid concentrations. Minor pathways may be specific to certain parts of plants; these can be either identical to the vertebrate pathway