What role does the enzyme glutamine synthetase play in ammonia transport?
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Glutamine synthetase adds ammonia to glutamate to form glutamine, which can move into the blood and transport ammonia to the liver.
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What role does the enzyme glutamine synthetase play in ammonia transport?
Glutamine synthetase adds ammonia to glutamate to form glutamine, which can move into the blood and transport ammonia to the liver.
What activates carbamoyl phosphate synthetase 1 (CPS1)?
N-acetylglutamate allosterically activates CPS1, increasing its affinity for ammonia.
What is the role of ornithine transcarbamoylase in the urea cycle?
Ornithine transcarbamoylase combines ornithine with carbamoyl phosphate to form citrulline in the urea cycle.
What happens to glutamine once it reaches the liver?
In the liver, glutamine is cleaved back into glutamate and ammonia by the enzyme glutaminase, allowing ammonia to enter the urea cycle.
How does ammonia get transported to the liver?
Ammonia is transported to the liver by being converted into glutamine or glutamate, which can then enter the bloodstream.
What is the role of aspartate in the urea cycle?
Aspartate provides the second nitrogen group necessary for the formation of urea in the urea cycle.
What happens to arginine in the urea cycle?
Arginine is broken down by arginase to produce urea and ornithine.
What is the major toxin resulting from the metabolism of amino acids?
Ammonia is the major toxin that results from the metabolism of amino acids.
What is the final product of the urea cycle?
The final product of the urea cycle is urea, which is less toxic and can be excreted by the kidneys.
What is the first step of the urea cycle?
The first step involves the enzyme carbamoyl phosphate synthetase 1 (CPS1) converting ammonia, carbon dioxide, and ATP into carbamoyl phosphate.
What is the significance of N-acetylglutamate in the urea cycle?
N-acetylglutamate is crucial for the activation of CPS1, and a deficiency can lead to toxic levels of ammonia.
The major toxin resulting from the metabolism of amino acids is ___.
ammonia
A genetic deficiency in N-acetylglutamate can lead to ammonia building up to ___ levels.
toxic
The enzyme ___ breaks down argininosuccinate into fumarate and arginine.
argininosuccinate lyase
The urea cycle converts ammonia into ___.
urea
Ammonia is transported to the liver through the blood by ___ and ___.
glutamine, alanine
The enzyme ___ combines ornithine with carbamoyl phosphate to form citrulline.
ornithine transcarbamoylase
In the urea cycle, aspartate provides the ___ nitrogen group necessary to form urea.
second
N-acetylglutamate allosterically activates CPS1, increasing the rate of ___ synthesis.
urea
The first step of the urea cycle involves the enzyme ___, which converts ammonia, carbon dioxide, and ATP into carbamoyl phosphate.
carbamoyl phosphate synthetase 1 (CPS1)
Urea is excreted by the ___ after being formed in the liver.
kidneys
Which amino acid will directly enter the urea cycle?
Aspartate
How does fumarate regenerate aspartate?
Fumarate is first converted to malate , and then the enzyme malate dehydrogenase converts malate to oxaloacetate. Oxaloacetate and glutamate are converted to aspartate and alpha-ketoglutarate by the enzyme aspartate transaminase, or AST. This regenerates aspartate, so that it may enter the next urea cycle.
