Urea Cycle

   I. Ammonia bad
      A. in brain
      B. ions

  II. Excretory strategies
      A. Ammonotelic
      B. Ureotelic
      C. Uricotelic

 III. History

  IV. Pre-step
      A. carbamoyl phosphate synthase I (CPS I)
      B. carbamoyl phosphate

   V. Urea cycle
      A. Step 1
         1. ornithine transcarbamoylase
         2. citruline
      B. Step 2
         1. argininosuccinate synthase
         2. argininosuccinate
      C. Step 3
         1. arginosuccinase
         2. arginine + fumarate
      D. Step 4
         1. arginase
         2. urea + ornithine

  VI. Clinical Insights
      A. Inherited defects
      B. Liver damage
      C. Hibernation