Here's how the acronym corresponds to the steps of the cycle:

• Ornithine reacts with Carbamoyl phosphate to form Citrulline (mitochondria).
• Citrulline reacts with Aspartate to form Argininosuccinate (cytosol).
• Argininosuccinate is cleaved to form Arginine and Fumarate.
• Arginine is hydrolyzed to form Urea, and ornithine is regenerated to continue the cycle.

You can remember OCCAAFAU as

• One – Ornithine (O-ne)
• Crazy - Carbamoyl phosphate (C-r-a-y)
• Chick - Citrulline (Ci-)
• Ate - Aspartate (-ate)
• And – Arginino+(and)+succinate – cleaves into:
• Fucked – Fumarate (Fu-)
• An – Arginine (A-n), which is hydrolyzed into
• Uncle – Urea (U-e)