Molecular vestigial characters

Molecular vestigial characters - Molecular vestigial...

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Molecular vestigial characters Vestigial characters should also be found at the molecular level. Humans do not have the capability to synthesize ascorbic acid (otherwise known as Vitamin C), and the unfortunate consequence can be the nutritional deficiency called scurvy. However, the predicted ancestors of humans had this function (as do most other animals except primates and guinea pigs). Therefore, we predict that humans, other primates, and guinea pigs should carry evidence of this lost function as a molecular vestigial character ( nota bene : this very prediction was explicitly made by Nishikimi and others and was the impetus for the research detailed below) (Nishikimi et al . 1992 ; Nishikimi et al . 1994 ). Confirmation: Recently, the L-gulano-γ-lactone oxidase gene, the gene required for Vitamin C synthesis, was found in humans and guinea pigs (Nishikimi et al . 1992 ; Nishikimi et al . 1994 ). It exists as a pseudogene, present but incapable of functioning (see prediction 4.4 for more about pseudogenes). In fact, since this was originally written the vitamin C pseudogene has been found in other primates, exactly as predicted by evolutionary theory. We now have the DNA sequences for this broken gene in chimpanzees, orangutans, and macaques (Ohta and Nishikimi 1999 ). And, as predicted, the malfunctioning human and chimpanzee pseudogenes are the most similar, followed by the human and orangutan genes, followed by the human and macaque genes, precisely as predicted by evolutionary theory. Furthermore, all of these genes have accumulated mutations at the exact rate predicted (the background rate of mutation for neutral DNA regions like pseudogenes) (Ohta and Nishikimi 1999 ). There are several other examples of vestigial human genes, including multiple odorant receptor genes (Rouquier et al . 2000 ), the RT6 protein gene (Haag et al . 1994 ), the galactosyl transferase gene (Galili and Swanson 1991 ), and the tyrosinase-related gene (TYRL) (Oetting et al . 1993 ). Our odorant receptor (OR) genes once coded for proteins involved in now lost olfactory
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This note was uploaded on 11/14/2011 for the course BIO BSC1010 taught by Professor Gwenhauner during the Fall '10 term at Broward College.

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Molecular vestigial characters - Molecular vestigial...

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