The citric acid cycle is the final common pathway for...
The oxidation of fuel molecules
The citric acid cycle oxidizes ______ to ______.
Acetyl CoA to CO2
The function of the citric acid cycle is to __________ from carbon fuels in form of NADH and FADH2
Harvest high-energy electrons
The citric acid cycle is strictly....
Citric acid cycle consists of 2 stages:
Oxidation of the 2 carbon atoms to 2 CO2
Regeneration of oxaloacetate.
Both stages of the citric acid cycle generate...
High-energy electrons that are used in oxidative phosphorylation.
Stage1 of Citric Acid Cycle:
Acetyl CoA + Oxaloacetate --> Citryl CoA (Int) --> Citrate
Citrate synthase exhibits...
*Leads to formation of the binding site for acetyl CoA
Step 2 of Citric Acid Cycle:
Citrate --> cis-Aconitate (Int) --> Isocitrate
_______ catalyzes the formation of isocitrate from citrate
Step 3 of Citric Acid Cycle
Isocitrate --> Oxalosuccinate (unstable int) --> a-Ketoglutarate
*First reaction where CO2 and NADH produced
_________ catalyzes the oxidative decarboxylation of isocitrate to a-ketoglutarate
Step 4 of Citric Acid Cycle
a-Ketoglutarate --> Succinyl CoA
*Produces CO2 and NADH
_________ catalyzes the formation of succinyl CoA by oxidative decarboxylation of a-ketoglutarate.
a-ketoglutarate dehydrogenase complex
Stage 2: Step 5 of Citric Acid Cycle
Succinyl CoA --> Succinate + GTP
*High phosphoryl potential
_______ catalyzes the cleavage of succinyl CoA to form succinate and GTP.
Succinyl CoA synthetase
Step 6 of Citric Acid Cycle
Succinate --> Fumarate
by succinate dehydrogenase
Step 7 of Citric Acid Cycle
Fumarate --> Malate
Step 8 of Citric Acid Cycle
Malate --> Oxaloacetate + NADH
by malate dehydrogenase
The citric acid cycle produces
High-transfer potential electrons
The NADH and FADH2 formed in the citric acid cycle are oxidized by...
The electron transport chain
How many ATP generated per NADH? per FADH2?
2.5 ATP per NADH
1.5 ATP per FADH2
1 Acetyl unit generates _____ molecules of ATP.
Citric acid cycle is the __________ for aerobic oxidation of fuel molecules and is a source of _______.
Final common pathway; building blocks
The key control points in the citric acid cycle are the reactions catalyzed by...
Isocitrate dehydrogenase and α-ketoglutarate dehydrogenase.
Control Point 1: Isocitrate dehydrogenase is allosterically activated by ____ and inhibited by ____.
Activated by ADP
Inhibited by NADH and ATP
Control Point 2: a-Ketoglutarate dehydrogenase is inhibited by _______.
Rate of citric acid cycle is reduced when the cell has...
High levels of ATP and NADH.
Many of the components of the citric acid cycle are...
Precursors for biosynthesis of key biomolecules.
Intermediates of the Citric Acid Cycle must be replinished. Replenishing reactions are called...
An example of anaplerotic reaction is the carboxylation of...
Pyruvate by pyruvate carboxylase
Defects in succinate dehydrogenase, fumarase or pyruvate dehydrogenase kinase can contribute to the development of _____.
These defects contribute to use of aerobic glycolysis (Warburg effect) by cancer cells leading to production of _____.
The glyoxylate cycle is similar to the citric acid cycle but bypasses the _________, allowing the synthesis of carbohydrates from fats.
Two decarboxylation steps
The glyoxylate cycle has two specific enzymes that are not present in the citric acid cycle:
The glyoxylate cycle has 2 acetyl CoA enter per cycle and leave as _____.
(Which can then be converted to glucose)
During the Citric Acid Cycle ATP or GTP is produced in the conversion of:
Succinyl CoA to Succinate
Which enzyme is NOT found in the Glyoxylate Cycle?
- Citrate synthase
- Isocitrate lyase
- Malate synthase
- Isocitrate dehydrogenase
Which citric acid cycle enzyme catalyzes the production of GTP?
Which enzyme converts citrate to isocitrate?
Which enzyme catalyzes the first oxidative decarboxylation reaction in the citric acid cycle and produces CO2?
Which compound inhibits the pyruvate dehydrogenase complex when present at high concentrations?
- Fructose 2,6-bisphosphate
Which citric acid cycle enzyme catalyzes the production of FADH2?
In the citric acid cycle, the first NADH is synthesized by the ________________reaction.
T or F: The purpose of the citric acid cycle is to convert acetyl CoA to fatty acids.
T or F: The rate of the citric acid cycle is reduced when the cell has high levels of NADH.
In the citric acid cycle, GDP is phosphorylated to GTP during the conversion of ________________ to ________________.
Succinyl CoA to Succinate
Which citric acid cycle enzyme catalyzes the production of GTP or ATP?
Succinyl CoA Synthetase
T or F: During the citric acid cycle FADH2 is produced by the enzymatic reaction catalyzed by fumarase.