L7 Citric Acid Cycle Flashcards
What are the three stages of cellular respiration?
(1) Acetyl-CoA production
(2) Acetyl-CoA oxidation
—-Citric acid cycle/ Tricarboxylic acid cycle/ Kreb cycle
(3) Electron transfer and oxidative phosphorylation
What are the reduced e- carriers?
NADH and FADH2
Which stage generates H2O?
Electron transfer and oxidative phosphorylation
Where does the transformation of acetyl-CoA from pyruvate occurs?
Inside mitochondria’s matrix
The enzyme complex responsible for transforming pyruvate to acetyl-CoA have how many components?
3
What is the overall feature of transforming acetyl-CoA from pyruvate?
Oxidative decarboxylation
What are the 5 cofactors involved in the transformation of acetyl-CoA from pyruvate?
(1) Thiamine pyrophosphate (TPP)
(2) Lipoic acid
(3) Coenzyme A
(4) Flavin adenine dinucleotide (FAD)
(5) Nicotinamide adenine dinucleotide (NAD+)
What is E1 in the enzyme complex called?
Pyruvate dehydrogenase
What are the two reactions that E1 catalyzes?
(1) Decarboxylation of pyruvate
(2) Transfer of acetyl group to lipoamide, which is a prosthetic group in E2
What is E2 in the enzyme complex called?
Dihydrolipoamide acetyltransferase
What is the reaction that E2 catalyzes?
Transfer of acetyl group to co-enzyme
When Arsenite (As) poisoning occurs, which component of the enzyme complex is inhibited?
E2
What is E3 in the enzyme complex called?
Dihydrolipoamide dehydrogenase
What are the two reactions that E3 catalyzes?
(1) Regeneration of lipoamide (oxidized form)
(2) Regeneration of FAD
Which two components of the enzyme complex are affected by the product inhibition and substrate activation?
E2 and E3
By which process is subunit E1 is regulated?
Phosphorylation
alpha- Ketoglutarate dehydrogenase complex resembles which enzyme in both structure and function?
Pyruvate dehydrogenase complex
What are the similarity and differences between Synthetases and Synthase?
Similarity: Both types of enzymes are involved in joining substrates together
Differences:
(1) Synthase reactions do not require NTP (nucleotide triphosphates)
(2) Synthetase reactions use NTP (ATP or GTP) as energy source
What is the strong inhibitor of succinate dehydrogenase?
Malonate, which is structurally similar to succinate
How many ATP equivalents are generated in one TCA cycle?
10
2 NADH can result in how many ATP in the following electron transport chain process?
5 ATP
2 FADH2 can result in how many ATP in the following electron transport chain process?
3 ATP
What is the net profit of aerobic degradation of glucose?
32 ATP
What are the four enzymes that are mainly being regulated in the citric acid cycle?
(1) Pyruvate dehydrogenase complex
(2) Citrate synthase
(3) Isocitrate dehydrogenase
(4) alpha-ketoglutarate dehydrogenase
Give me the flow of metabolites in TCA.
Oxaloacetate + Acetyl-CoA → Citrate → Isocitrate → alpha- ketoglutatrate → Succinyl-CoA → Succinate → Fumarate → Malate → Oxaloacetate
In TCA cycle, which enzyme is the only membrane-bound enzyme?
Succinate dehydrogenase
Malonate can effectively blocks TCA cycle activities because it is a strong analog of which metabolite and a strong inhibitor of which enzyme?
Because malaonate is a srong analog of succinate and a strong in hibitor of succinate dehydrogenase
alpha-Ketoglutarate dehydrogenase complex resembles which enzyme in both structure and function?
Pyruvate dehydrogenase
What is the link between glycolysis and TCA cycle?
Production of acetyl-CoA from pyruvate
