Final answer:
The end product of purine metabolism in humans is uric acid, with conditions like Lesch-Nyhan syndrome and Von-Gierke's disease affecting uric acid levels.
Step-by-step explanation:
The end product of purine metabolism in humans is uric acid. In other species such as birds and reptiles, uric acid may be further broken down into allantoins. However, in humans and some other primates, uric acid is the final product and is excreted in the urine. Conditions such as Lesch-Nyhan syndrome and Von-Gierke's disease can affect uric acid levels in humans. Lesch-Nyhan syndrome features a lack of the enzyme HGPRT, resulting in increased degradation of purines to uric acid. Conversely, Von-Gierke's disease leads to overproduction of uric acid due to an overactive HMP shunt pathway.