Urea cycle and disorder and formation of ammonia.

1. UREA
CYCLE
SNEHITA PRASAD
LECTURER, Department of Biochemistry
Narsinhbhai patel dental college & hospital
SPU

2. * Ammonia is produced in most tissues – less than 1% is TOXIC especially to
CNS
Readily ionizes to ammonium ion NH4
+
* It is immediately removed from the circulation and detoxified to Urea in
the LIVER.
* Three transport forms of NH3 from peripheral tissues to LIVER:
1. Glutamate – ALL tissues
2. Glutamine – Brain
3. Alanine - Muscle

10. EXCRETARY FORM OF NITROGEN
Mammals including human
beings
The basic features
of nitrogen
metabolism were
elucidated initially
in pigeons

11. UREA CYCLE
Elimination of ammonia or Removal of ammonia.
Krebs–Henseleit urea cycle / Ornithine cycle
Site – LIVER
Subcellular organelle – Mitochondria , cytoplasm – 2 steps occur in
mitochondria, remaining in the cytosol.
Converts NH3 into harmless Urea

15. The toxic ammonia is converted into the harmless nontoxic urea.
• It disposes off two waste products, ammonia and CO2
It forms semi-essential amino acid, arginine, Histidine
It participates in the regulation of blood pH, which depends upon the ratio
of dissolved CO2, i.e. H2CO3 to HCO3 – .
Ornithine which is formed in urea cycle can form nonessential
amino acid proline
SIGNIFICANCE OF UREA CYCLE

23. TREATMENT