Nitrogen Flashcards
What do amino acids and nucleotides contain that carbohydrates and fats don’t?
Nitrogen!
What is nitrogenase inactivated by?
Oxygen
Which is the only amino acid that can obtain its nitrogen directly from NH4?
Glutamate
What is the name of the process of incorporating nitrogen from glutamate into proteins and nucleotides?
Assimilation
How do organisms conserve N2?
Transferring amino groups between different molecules - transamination
Is transamination readily reversible?
Yes
Do transaminases participate in amino acid synthesis or degradation?
Both
What is pyridoxal phosphate?
A cofactor made from vitamin B6, required by all aminotransferases
Which enzymes transfer NH4 from glutamate to other amino acids?
Aminotransferases
Ammonia is transported in the bloodstream safely as _________
Glutamine
Why is glutamate made, then converted into glutamine or alanine, only to be converted back in the liver?
Glutamate is negatively charged, whereas alanine and glutamine are uncharged. Charged molecules don’t pass through membranes easily, hence conversion to uncharged molecules allows easy transport.
Where is excess glutamate metabolised?
Mitochondria of hepatocytes
What are the 9 essential amino acids needed in the diet?
Histidine Isoleucine Leucine Lysine Methionine Phenylalanine Threonine Tryptophan Valine
Which amino acids are both glucogenic and ketogenic?
Isoleucine, tyrosine and phenylalanine
Name four clinical features of inherited metabolic disorders presenting in childhood
- Acidosis
- Failure to thrive
- Vomiting, refusal of feeds, irritability
- Central nervous system dysfunction
- Hypoglycaemia
- Unusual odour
