Nitrogen metabolism 2

What is transamination?
The transfer of an amino acid from one compound to another
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Describe the process of transamination
NH2 is transferred from amino acid to keto acid to form new amino acid, (Enzymes: Transaminases and aminotransferases), Pyridoxal phosphate as co-enzyme to transfer -NH2 group, allows plants and microbes to synthesise all amino acids needed
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What is the primary source of NH2?
Glutamate
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What 3 keto acids react with glutamate? (The 3 for the exam)
Pyruvate, 3-phosphoglycerate and oxaloacetate
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What is pyruvates -R group and what happens when it reacts with glutamate?
-CH3, and it forms alanine
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What is 3-phosphoglycerates -R group and what happens when it reacts with glutamate?
-CH2OH, and it forms serine
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What is oxaloacetates -R group and what happens when it reacts with glutamate?
-CH2COOH, and forms aspartate
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What are the sources of keto acids for amino acid synthesis?
Intimidates from both carbohydrate and lipid metabolism
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What happens when animals eat excess amino acids?
They cannot be stored so they must be degraded
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What are the 2 stages of degradation?
Deamination and oxidative deamination
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Deamination
-NH2 group from the amino acid being degraded is transferred to 2-oxo-glutarate to form glutamate
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Oxidative deamination
-NH2 group of glutamate is removed by glutamate dehydrogenase
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What happens to the keto acids during deamination?
They are fed into the central metabolic pathways (If glucogenic, they can be used as a substrate for glucose synthesis, if ketogenic they can be used to synthesise ketone bodies)
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What is the urea cycle?
The production of NH3 into urea, as NH3 can be toxic to animals
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Where does the urea cycle take place?
The liver
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Step 1
In mitochondria- Requires 2 ATP, (Enzyme: carbamoyl phosphate synthetase), Product: Carbamoyl phosphate
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Step 2
Mitochondria- Ornithine reacts with carbamoyl phosphate to form citrulline, (Enzyme: Ornithine transcarbamoylase), Citrulline moves out of mitochondria into cytoplasm
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Step 3
Cytoplasm- Aspartate (amino acid) joins citrulline, product: Argininosuccinate
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Step 4
Cytoplasm- Argininosuccinate splits to form fumerate and arginine (amino acid), fumerate goes into TCA cycle
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Step 5
Cytoplasm- Arginine is broken down with H2O to form urea and ornithine, ornithine is shuttled back into kidneys and urea is excreted by kidneys
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Other cards in this set

Card 2

Front

Describe the process of transamination

Back

NH2 is transferred from amino acid to keto acid to form new amino acid, (Enzymes: Transaminases and aminotransferases), Pyridoxal phosphate as co-enzyme to transfer -NH2 group, allows plants and microbes to synthesise all amino acids needed

Card 3

Front

What is the primary source of NH2?

Back

Preview of the front of card 3

Card 4

Front

What 3 keto acids react with glutamate? (The 3 for the exam)

Back

Preview of the front of card 4

Card 5

Front

What is pyruvates -R group and what happens when it reacts with glutamate?

Back

Preview of the front of card 5
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