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24 Cards in this Set
- Front
- Back
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What are the regulatory points in the citric acid cycle?
Four points... |
1. Pyruvate dehydrogenase
2. Citrate synthase 3. Isocitrate dehydrogenase 4. α-ketoglutarate dehydrogenase |
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What allosterically regulates citrate synthase,isocitrate dehydrogenase, and
α-ketoglutarate dehydrogenase? How is it repressed/activated? |
1. Repressed by high energy levels (ATP, NADH)
2. Activated by low energy levels (ADP, NAD+) |
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What molecules inhibit citrate synthase and α-ketoglutarate through feedback inhibition?
Two molecules... |
1. Citrate
2. Succinyl CoA |
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What happens to the citric acid cycle if all of the intermediates are use for biosynthesis?
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Cycle will stop
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Will adding more acetyl-CoA replenish the intermediates in the citric acid cycle?
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No it will not because the pathway is cyclic
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How are intermediates in the citric acid cycle replenished?
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Anaplerotic reactions
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What are anaplerotic reactions?
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Four ways to convert either pyruvate or PEP directly to citric acid cycle intermediates without passing through acetyl-CoA
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What are the enzymes for each anaplerotic reaction?
Four molecules... |
1. Pyruvate carboxylase
2. PEP carboxykinase 3. PEP carboxylase 4. Malic enzyme |
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What is the product of the anaplerotic reaction using pyruvate carboxylase?
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Oxaolacetate
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What intermediate is formed from the anaplerotic reaction catalyzed by PEP carboxykinase?
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Oxaolacetate
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PEP carboxylase catalyzes an anaplerotic reaction that produces what intermediate?
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Oxaolacetate
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The malic enzyme catalyzes an anaplerotic reaction that converts pyruvate into what intermediate?
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Malate
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What is biotin?
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Biotin is the cofactor for carrying oxidized single carbons
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What compound are fatty acids degraded into?
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Acetyl-CoA
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What does the glyoxylate shunt allow to happen?
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Shunt converts fat to glucose
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How is the glyoxylate shunt able to convert fat to glucose?
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It bypasses the two steps in the citric acid cycle that release CO2 so that there's a net increase in C
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Can mammals make glucose from fat?
Why or why not? |
No because we do not have isocitrate lyase and malate synthase
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Where is the glyoxylate shunt located in plants?
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In the glyoxysome organelle next to the mitochondria
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What is the function of the glyoxylate shunt?
Two functions... |
1. It splits isocitrate and directly form malate and succinate
2. It allows the reversal of the pyruvate dehydrogenase step |
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What happens to isocitrate after it is split?
Two things... |
1. Succinate is converted to PEP and used for gluconeogenisis
2. Malate is used to keep the citric acid cycle running |
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What vitamin is biotin?
Why is a lack of biotin uncommon? |
Vitamin H
The bacteria in our intestines makes biotin |
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What is pantothenate?
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Vitamin B-5
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What is pantothenate required for?
Two things... |
1. Acetyl-CoA
2. Acyl carrier protein |
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What is the difference between biotin and TPP?
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Biotin's active site is CO2
TPP's active site is an acetaldehyde |
