Amino acid catabolism Flashcards
What is catabolism?
the breakdown of complex molecules in living organisms to form simpler ones, together with the release of energy
can amino acids be stored if not needed?
No, they are degraded
Where does amino acid degradation happen?
In the liver
Where do most of the amino acids come from?
From the diet - absorption
Protein turnover - damaged proteins have to be removed, regulation of protein activity also so get rid of those you dont need
what is the main problem for amino acid breakdown?
They contain Nitrogen in their side chains as well as their basic structure not all
What does the breakdown of amino acid produce?
Ammonia and ammonium ions, high concentrations these become toxic (contain nitrogen)
what is toxic at high levels?
Ammonium NH4+
What is the main nitrogen containing excreting molecule?
Urea - formed in liver, main excretion molecule for nitrogen, 80% excreted via urea
Where is urea produced?
In the LIVER
What is transamination? (CHECK)
First step in synthesis of urea
Amino acids are transferred to ketone acids
usually forms glutamic acid
What is de-amination? (CHECK)
Occurs only in the liver
Removal of amino acid from ketone acid
leaving alanine of glutamine
Free ammonium ion
What are the main transport molecules for nitrogen in the blood to the liver?
Alanine and glutamine
What is the final step of the urea cycle?
The ammonium enters the urea cycle
What is the remainder called once the amino group has been removed from the amino acid?
Carbon skeleton
What happens to the carbon skeletons?
They are converted to major metabolic intermediates
Or can be converted to glucose or oxidised in the TCA cycle
What are the different types of amino acids?
Ketogenic amino acids
Glucogenic amino acids
Describe ketogenic amino acids
degrated to acetyl CoA or acetoacetly CAN give rise to ketone bodies or fatty acids CANNOT enter gluconeogenesis
Describe glycogenic amino acids?
degraded to pyruvate or TCa cycle intermediated CAN be converted into phosphoenlopyruvate and then into glucose CAN enter gluconeogenesis
