My revision notes: A2 Biology: Urea + Ornithine cycle + detoxification of alcohol

Deamination is the process where ammonia (NH3) is produced. Ammonia is very soluble and highly toxic. It also produces an organic keto acid which is then used in respiration. Ammonia is converted into Urea which is less soluble and less toxic. Urea travels in the blood and is transported to the kidneys where it is filtered out of the blood and stored into the bladder until released from the body.

The ornithine cycle

2NH + CO2 > CO(NH2)2 + H2O

ammonia + carbon dioxide > urea + water

Detoxification of alcohol

Alcohol can be bad for us but it also contains chemical potential energy which could be used in respiration.

• Alcohol is broken down b hepatocytes by the action of enzyme ehtanol dehydrogenase
• In result of this ETHANAL is made
• it is then dehydrogenated again by ethanal dehydrogenase
• Which produces ethanoate (acetate)
• combined with coenzyme A to form acetyl coenzyme A which enters respiration.
• Ethanol > Ethanal > Ethanoic acid > Acetyl coenzyme A