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What are other common names for the citric acid cycle?
TCA cycle and Krebs cycle
What is the citric acid cycle?
completes the breakdown of glucose
Where does the TCA cycle occur?
mitochondrial matrix
What does acetyl CoA combine with in the citric acid cycle?
Oxaloacetate to make a 6 Carbon intermediate
Net reaction of TCA cycle?
acetyl CoA + 3NAD+ + FAD + GDP + Pi + H20 --> 3NADH + FADH2 + GTP + CoA + 2CO2
What are the products of TCA?
3 NADH
1 FADH2
1 GTP
2 CO2
What is oxidative phosphorylation?
Uses energy released by the electron transport chain to power ATP synthesis.
Where are the enzymes for the TCA cycle?
all are floating in mitochondrial matrix except one is bound to the inner mitochondrial matrix
Step 1 of TCA cycle? Cofactors?
Oxaloacetate --> Citrate
Cofactors: Acetyl CoA --> + CoA
What enzyme catalyzes step 1 of TCA cycle?
Citrate Synthase
What kind of reaction is step 1 of TCA cycle?
Condensation
Step 2 of TCA cycle? Cofactors?
Citrate --> Isocitrate
Cofactors: H2O --> H20
What enzyme catalyzes step 2 of TCA cycle? what happens?
aconitase. removes water molecule and reattch at different carbon
What kind of reaction is step 2 of TCA cycle?
Dehydration, rehydration
Step 3 of TCA cycle? Cofactors?
isocitrate --> alpha-ketoglutarate
Cofactors: NAD+ --> NADH + CO2
What enzyme catalyzes step 3 of TCA cycle?
isocitrate dehydrogenase
What kind of reaction is step 3 of TCA cycle?
oxidative and decarboxylation
Step 4 of TCA cycle? Cofactors?
alpha-ketoglutarate --> succinyl-coA
Cofactors: NAD+ + CoA --> NADH + CO2
What enzyme catalyzes step 4 of TCA cycle?
alpha-ketoglutarate dehydrogenase complex
What kind of reaction is step 4 of TCA cycle?
Oxidative decarboxylation
Step 5 of TCA cycle? Cofactors?
succinyl-CoA --> succinate
Cofactors: ADP + Pi --> ATP + CoA
What enzyme catalyzes Step 5 of TCA cycle?
succinyl-CoA synthetase
What kind of reaction is step 5 of TCA cycle?
substrate level phosphorylation
Step 6 of TCA cycle? Cofactors?
succinate --> fumarate
Cofactors: FAD --> FADH2
What enzyme catalyzes step 6 of TCA cycle?
Succinate dehydrogenase
What kind of reaction is step 6 of TCA cycle?
Dehydrogenation
Step 7 of TCA cycle? Cofactors?
fumarate --> malate
Cofactors: H20
what enzyme catalyzes step 7 of TCA cycle?
fumarase
what kind of reaction is step 7 of TCA cycle?
hydration
Step 8 of TCA cycle? Cofactors
malate --> oxaloacetate
Cofactors: NAD+ --> NADH
What enzyme catalyzes step 8 of TCA cycle?
Malate Dehydrogenase
What kind of reaction is step 8 of TCA cycle?
Dehydrogenation
One turn of the TCA cycle
-two carbons enter
(acetyl CoA)
-2 carbons leave via 2 CO2 from oxaloacetate
-3 NADH
-1 FADHS
-1 GTP = ATP
-Oxaloacetate regenerated
what does the oxidation of glucose yield?
2 pyruvate
How many ATP does NADH yield?
2.5 ATP
How many ATP does FADH2 yield?
1.5 ATP
What regulates the TCA cycle?
phosphorylation of pyruvate dehydrogenase
TCA cycle enzymes. the two irreversible reactions
what reactions are not reversible in TCA cycle?
-isocitrate dehydrogenase
-alpha-ketoglutarate dehydrogenase
activators and inhibitors of isocitrate dehydrogenase
Activators: ADP
Inhibitors: ATP and NADH
Inhibitors of alpha-ketoglutarate dehydrogenase
ADP, Succinyl CoA, NADH
What can Citrate be used for other than the TCA cycle?
Fatty acids and sterols
What can alpha-ketoglutarate be used for other than the TCA cycle?
Glutamate --> other amino acids --> Purines
What can Succinyl CoA be used for other than the TCA cycle?
Porphyrins, heme, chlorophyll
What can Oxaloacetate be used for other than the TCA cycle?
Amino acids
What are anaplerotic reactions?
Reactions that replenish citric acid cycle intermediates
Anaplerotic carboxylase reaction in TCA cycle
Pyruvate carboxylase (idk)
Pyruvate undergoing carboxylation to make oxalaoacetate
What does fluoroacetate do to the TCA cycle?
inhibits aconitase and the formation of isocitrate
Why is the inhibition of aconitase detrimental?
blocks the TCA cycle
accumulation of Citrate and energy depletion
seizures
What is the glyoxylate cycle?
It is similar to the citric acid cycle but bypasses the two decarboxylation steps, allowing the synthesis of carbohydrates from fats
When is the glyoxylate cycle highly active in oil seed plants?
During germination because it helps synthesize energy before they can photosynthesize
Where does the glyoxylate cycle occur?
glyoxysomes
Glyoxylate cycles main function?
produce succinate to be converted to oxaloacetate and then into glucose
Step 1 of glyoxylate cycle? Cofactors?
oxaloacetate --> Citrate
Cofactors: Acetyl CoA + H20 --> CoA
What enzyme catalyzes step 1 of glyoxylate cycle?
Citrate Synthase
Step 2 of glyoxylate cycle? Cofactors?
Citrate --> Isocitrate
Cofactors: H20 --> H20
What enzyme catalyzes step 2 of glyoxylate cycle? What happens?
Aconitase. Removes water molecule and reattach at different carbon
What kind of reaction is step 2 of the glyoxylate cycle?
Dehydration, Rehydration
Step 3 of glyoxylate cycle?
Isocitrate --> Succinate + Glyoxylate
What happens to the succinate produced in the glyoxylate cycle?
Goes into the mitochondria and enters the citric acid cycle
What enzyme catalyzes step 3 of the glyoxylate cycle?
Isocitrate lyase
What does a lyase enzyme do?
One molecules is broken down into two
Step 4 of glyoxylate cycle? Cofactors?
Glyoxylate --> Malate
Cofactors: Acetyl CoA + H20 --> CoA
What enzyme catalyzes step 4 of the glyoxylate cycle? what happens?
Malate Synthase. Glyoxylate condenses with acetyl CoA
Step 5 of the glyoxylate cycle? Cofactors?
Malate --> Oxaloacetate
Cofactors: NAD+ --> NADH + H+
What enzyme catalyzes step 5 of the glyoxylate cycle? what happens?
Malate dehydrogenase. Malate is oxidized
What reactions are bypasses in the glyoxylate cycle?
Isocitrate dehydrogenase and the alpha-ketoglutarate dehydrogenase reactions
What does one cycle of the glyoxylate cycle use and produce?
2 Acetyl CoA and produces 1 succinate
What 4 pathways are involved in conversion of fat to glucose in plants?
Glyoxylate cycle and Citric Acid cycle overall reactions?
(Lipid Body) TAG--> FA --(Glyoxysome)--> Acetyl CoA--> Succinate-- (Mtio) --> Malate --(Cytoplasm)--> Oxaloacetate --> Glucose
What are the two different enzymes in the glyoxylate cycle compared to the TCA cycle?
Isocitrate lyase and Malate synthase