14 – citric acid cycle/Tricarboxylic acid cycle/Krebs Cycle Flashcards
what enters the CAC
acetyl CoA
3 carbons of pyruvate are…
lost
1 CO2 released from making Acetyl CoA
2 CO2 released from Citric Acid Cycle
Makes NADH
-during transformation of oyruvtae to acetyl CoA
-3 NADH produced in CAC
-1 NADH by special transporter
Makes FADH2
one in CAC
Pyruvate – enter mitochondria –>
TCA cycle as a C2 ACETYL GROUP ON ACETYL-COA
what is the 3 step reaction
- decarboxylation
- Oxidation – create 1 NADH
- Transfer of acetylene group
what is a large complex
Pyruvate dehydrogenase
TCA metabolites = source of
biosynthetic precursors & cofactors
Citric acid cycle steps:
1.Citrate synthase
C2 acetylene group – added to oxaloacetate (C4 “carrier”) = citrate
2.Aconitase
Citrate converted into less stable form (isocitrate)
Helps further reactions
3.Isocitrate dehydrogenase & α-ketoglutarate dehydrogenase
2 steps to break down C6 isocitrate into C4 succinyl CoA
-generates CO2 & NADH
succinyl-CoA synthetase + succinate dehydrogenase + fumarase + malate dehydrogenase
4 steps to convert C4 succinyl CoA to oxaloacetate
-makes FADH2 & NADH
…enable substrate channeling
Large metabolic complexes
2 carbons entering the cycle …leave on first go around
doesnt
To use it all, it may need to cycle a few times
TCA enzymes = can be & how
oncogenes
Mutation in isocitrate dehydrogenase – produce oncogenic metabolite
Glucose – fully converted into
Co2, NADH and few ATP
the CAC summary:
- in cytoplasm = make fatty acid available to mitochondria
2.pyruvtate & fatty acyl CoA has its own transporter - pyruvate -> acetyl CoA (lose CO2, make NADH, attach acetyl group to CoA)
- enter CAC - 2 CO2 leaves, produce 1 GTP/FADH2/3NADH
