TCA cycle

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Describe the link reaction.
pyruvate + CoA (S-H) --> acetyl CoA + Co2. using pyruvate dehydrogenase and NAD+. This forms a thioester.
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Which enzymes in the link reaction are said to be allosteric and what does this mean?
Allosteric enzymes are regulated by the binding of a molecule at a second site which regulates enzyme activity. These enzymes in the TCA cycle are, citrate synthase, isocitrate dehydrogenase and a-ketoglutrate dehydrogenase.
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In which tissues does TCA cycle take place?
All tissues with mitochondria, so not RBC or white muscle fibres as fast twitch fibres have little mitochondria as they respire anaerobically for quick energy release.
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What is the biosynthetic role of the TCA cycle?
compounds from the TCA cycle can be added or removed to balance metabolism when needed.
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What can oxaloacetate become?
For amino acid synthesis, it can become aspartate and then go on to become other amino acids, purines and pyrimidines.
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What can succinyl coA become?
Through haem synthesis it can become a haem group
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What can a-ketoglutarate become (also know as 2-oxoglutarate)
Through transamination it can become glutarate and then through amino acid synthesis it can become other amino acids and purines.
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What is transaminaiton?
the transfer of an amino group from one molecule to another, especially from an amino acid to a keto acid.
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What is anaplerotic topping up of the TCA cycle?
You need to add things back in if you take them out. Pyruvate can become oxaloacetate by adding CO2 with enzyme pyruvate carboxylase. Oxaloacetate can become PEP and go to make glucose (glycolysis reverse reaction)
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Continued.
From pyruvate you can use maltic enzymes to make maltate.
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What does glycogenic and ketogenic amino acids mean?
Glycogenic aa can be converted back to glucose by the liver, acetyl coA->glucose. Leucine and lycine are ketogenic so can only be degraded to ketone bodies not further.
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Card 2

Front

Which enzymes in the link reaction are said to be allosteric and what does this mean?

Back

Allosteric enzymes are regulated by the binding of a molecule at a second site which regulates enzyme activity. These enzymes in the TCA cycle are, citrate synthase, isocitrate dehydrogenase and a-ketoglutrate dehydrogenase.

Card 3

Front

In which tissues does TCA cycle take place?

Back

Preview of the front of card 3

Card 4

Front

What is the biosynthetic role of the TCA cycle?

Back

Preview of the front of card 4

Card 5

Front

What can oxaloacetate become?

Back

Preview of the front of card 5
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