Nitrogen Flashcards
In what form do humans excrete nitrogen?
Urea (amino acids) and Uric Acid (purines)
Why is glutamate converted into glutamine or alanine only to be converted back again in liver?
Glutamate has a negative charge where as alanine and glutamine have no charge. This allows them to pass through membranes readily. Easy transport.
How is ammonia recaptured after being bonded to glutamate?
After glutamate dehydrogenase reaction it produces alpha-ketoglutarate and NH4+ .
Ammonia is then recaptured via synthesis of Carbamoyl Phosphate
What are the 2 classes of amino acids in citric acid cycle?
Glucogenic - potential to form glucose
Ketogenic - potential to form ketones
Why can’t ketogenic amino acid carbon skeletons result in gluconeogenesis?
Pyruvate to Acetyl CoA is irreversible and so there is no net synthesis of oxaloacetate through CAC.
How is L-glutamine produced in the body?
Amino acids are catabolised by transferring the amino group to alpha-ketoglutarate via PLP dependent aminotransferase.
What are Inherited Metabolic Disorders?
Group of genetic diseases involving metabolic defects
Inherited metabolic disorders result in the abnormal synthesis or catabolism of what?
Proteins
Amino acids
Carbohydrates
Lipids
Name some common clinical features of IMDs present in childhood?
Acidosis Failure to thrive Vomiting & refusal of feeds CNS dysfunction Hypoglycaemia Unusual odour
Where does the urea cycle occur?
Spilt between mitochondrial matrix and cytosol
How many IMDs of the urea cycle are there?
6
What is transamination?
The transferring of amino groups between different molecules in order to conserve nitrogen stores.
What are some fates of nitrogen in organisms?
Humans and great apes excrete both urea (from amino acids) and uric acid (from purines).
How is ammonia safely transported in the bloodstream.
Converted to Glutamine by attaching to glutamate.
