what are citrulline and ornithine and do we come acrss these two in any metabolic cycle?

Answer 1

these are amino acids, they are in the urea cycle.

Answer 2

Citrulline is made from ornithine and carbamoyl phosphate in one of the central reactions in the urea cycle. It is also produced from arginine as a by-product of the reaction catalyzed by NOS family (NOS; EC 1.14.13.39). First arginine is oxidized into N-hydroxyl-arginine, which is then further oxidized to citrulline concomitant with release of nitric oxide.