BIOD33H3 Lecture Notes - Lecture 9: Alanine, Metabolic Waste, Oviparity
Document Summary
All of the proteins ingested and cellular proteins are broken down into amino acids, which are either used for growth/maintenance. The excess are catabolized and turn them into ammonia. Ammonia is generally toxic, which then needs to get rid of: aquatic organisms excrete it (ammonotely, terrestrial animals turn it into something else. The new forms are less toxic, and therefore can be stored for longer. Ammonia excretion relies on diffusion: excretory fluid must have a low concentration of ammonia, ammonia excretion requires a lot of water (~400x of uric acid) Urea is much less toxic in mammals: < 26mm. Uric acid is very semisolid (very little water in it: uric acid is virtually non-toxic to animals. No additional energy required to excrete just ammonia: urea has an energetic cost (~4 atp, uric acid is the most energy costly (~8-12 atp) Ammonia makes up the predominate waste in rainbow trout: ammonia is the predominate form of excretion in ammonotely.
