BioChem: TCA Cycle
Terms
undefined, object
copy deck
- How do aerobes generate energy?
-
-by using oxygen through:
-tricarboxylic acid cycle (TCA)
-Electron transport chain
-oxidative phosphorylation - What catalyzes the reaction of pyruvate entering the TCA cycle?
- -Pyruvate Dehydrogenase
- Describe Pyruvate Dehydrogenase
-
-contains three different activities
-uses five different coenzymes
-huge complex 4.6 million Da
(24 polypeptides of 1, 24 of 2, and 12 of 3) - What are the three different activities performed by Pyruvate Deyhydrogenase?
-
-pyruvate dexarboxylase OR pyruvate dehydrogenase
-dihydrolipoamide transacetylase
-dihydrolipoamide dehydrogenase -
Pyruvate Dexarboylase uses what?
And what does dihydrolipoamide transacetylase use? -
-thyamine pyrophosphate
-lipoic acid - What do Flavoproteins use Flavin Coenzymes as?
- -Electron Carriers
- What does reaction 1 do in the TCA cycle?
- -introduces 2 carbons
- What is known as a suicide substrate?
- -Fluoroacetate
- What does reaction 2 do in the TCA cycle?
- -isomerization of citrate
- Citrate is symmetrical, but what treats is asymmetrically?
- -aconitase
- What happens in reaction 3 in the TCA cycle?
- -Oxidation of Isocitrate
- What happens in reaction 4 in the TCA cycle?
- -oxidation of alpha-ketoglutarate
- What happens in reaction 5 in the TCA cycle?
- -cleavage of Succinyl-CoA
- What happens in reaction 6 in the TCA cycle?
- -Oxidation of succinate
- What happens in reaction 7 in the TCA cycle?
- -hydration of fumarate
- What occurs in reaction 8 of the TCA cycle?
- -oxidation of malate
- What are the highest energy yields developed from the TCA cycle?
-
-Isocitrate DH
-Ketoglutarate DH
-Malate DH -
What is the lowest energy yielding reaction from the TCA cycle?
How about the middle energy yield? -
-Succinyl-CoA Synthase
-succinate DH - What are the two problems with the TCA cycle?
-
1) How to get pyruvate into the mitochondria
2) How to get reducing power (NADH) into the mitochondria - What are two other functions of the TCA cycle?
-
-most important energy generating process in the cell
-TCA intermediates are starting materials for other important molecules in the cell - Why must the TCA cycle be tightly controlled?
- -it is the link between Glycolysis and the Electron Transport Chain
- How many sites are there for TCA control?
- -3
- What has the order from greatest free energy (-43.9) of TCA reactions to least (0.8)?
- -Citrate synthase > Alpha Ketoglutarate DH > Isocitrate DH > Malate DH, Fumarase, Succinate DH, Succinyl CoA Synthase > Aconitase
- Animals can not synthsize sugars from what?
- -Aceyl-CoA
-
What can some bacteria use as their only carbon source?
What type of seeds can grow with only stored fats? -
-acetate
-oil seed plants - What are some symptoms of Pyruvate Dehydrogenase Deficiency?
-
-children with pyruvate DH deficiency have elevated serum lactate, pyruvate, and alanine
-neurological defects
-treatment with dichloroacetate, inhibitor of Pyruvate DH kinase - What are some symptoms of Fumarase Deficiency?
-
-rare
-urine contains elevated amounts of fumarate, succinate, ketoglutarate, and citrate
-sufferers have severe neurological impairment and sydtionia developing soon after birth - What are two diseases of the TCA cycle.
-
-Pyruvate Dehydrogenase Deficiency
-Fumarase Deficiency - How can you make a table of Standard reduction potentials?
- -by using the standard hydrogen electrode
- What can the data from the half reactions be used for?
- -analyzing energy changes in redox reaction
- How do spontaneous reactions work?
- -electrons from the more negative reduction potential half-reaction are donated to the half-reaction with the more positive reduction potential