L15 - TCA cycle Flashcards
how is pyruvate converted to acetyl CoA
decarboxylated by pyruvate decarboxylase, oxidised by pyruvate dehydrogenase and combined with CoA producing
2x acetyl CoA
2x CO2
2x NADH + H+
what is the TCA cycle
oxidation of acetyl CoA
what tissues cant carry out TCA cycle and why
RBCs
white muscle fibres
no mitochondria
why is production of succinyl CoA useful (in TCA)
thioester bond stores alot of energy
functions of TCA cycle
production of ATP
production of NADH + H+
production of FADH2
why is reduction of NAD and FAD in krebs cycle useful?
they can both be re-oxidised in the ETC to produce more ATP
how many molecules of ATP are produced from the reoxidation of 1 molecule of NAD
2.5
how many molecules of ATP are produced from the reoxidation of 1 molecule of FAD
1.5
how many molecules of ATP are produced from the TCA cycle
2.5 x 3
1.5 x 1
1 x ATP
= 10 ATP per one cycle
what reactions of TCA cycle are highly exergonic and irreversible
- oxaloacetate + acetyl CoA —— citrate
- isocitrate - 2 oxo glutarate
- 2-oxo-glutarate - succinyl CoA
what components of the krebs cycle are involved in other biosynthesis pathways
a keto glutatrate
succinyl CoA
oxaloacetate
what can a keto glutarate be converted into and how
glutamate by transamination
then other AA’s and purines
what can succinyl CoA be converted into
haem
what can oxaloacetate be converted to and how
aspartate by transamination
then other AAs, purines and pyrimidines
how can the TCA cycle be topped up?
pyruvate can be converted to oxaloacetate by pyruvate carboxylase
