TCA Cycle (Catabolism of Pyruvate) Flashcards
What is the net energy and redox yield from aerobic glycolysis?
2ATP and 2NADH
What does glycolysis reduce?
NAD+ to NADH + H+
What needs to happen to NADH for glycolysis to continue?
Be oxidised to generate NAD+ = through oxidative metabolism of pyruvate
Why is NAD+ important?
Because is it an electron ACCEPTOR
Where does the TCA cycle occur?
In the mitochondrial MATRIX
How is pyruvate transported to mitochondrial matrix?
H+/pyruvate symport by faciliatated diffusion
H+ gradient from cytosol to matrix
How is pyruvate metabolised to acetyl-CoA?
By pyruvate dehydrogenase complex (PDC)
What does pyruvate dehydrogenase complex catalyse?
Oxidative decarboxylation of pyruvate to acetyle CoA
What does PDC consist of and how is it regulated?
Pyruvate dehydrogenase complex = made of 3 enzymes
Allosterically regulated by phosphorylation
What does PDC determine in well oxygenated tissues?***
Glucose oxidation
Where does PDc determine glucose oxidation?
In well oxygenated tissues
Can acetyl-CoA be converted back to pyruvate?
No, it is an irreversible reaction
What does the TCA cycle yield?
2 CO2 molecules
3 NADH molecules
1 FADH2 molecules
1 GTP
Where are enzymes of the TCA cycle located?
Mitochondrial matrix
What enzymes are located in the mitochondrial matrix?
Enzymes of TCA cycle
Except for sccinate dehydrogenase
Where is succinate dehydroganse found?
Integrated in the inner mitochondrial membrane
Which we shall see in oxidative phosphorylation
What reaction does succinate dehydrogenase catalyse?
succinate + FAD»_space;> fumarate + FADH2
What reaction forms GTP from GDP + Pi?
Substrate level phosphorylation
What regulates the TCA cycle?
High ATP and NADH (and acetyl-CoA)= lots of energy
High succinyl-CoA and acetyl-CoA = plenty of precurors
High ADP and NAD+ = low energy
What is PDC deficiency?
Stage II Metabolic Disorder
Gene located on X chromosome
So XY = still born
XX = adolscent onset; variable symptom severity
Pyruvate dehydrogenase complex deficiency symptoms
Neurological disease in childrem
Poor muscle tone and lack of coordination
Retardation and seizures
Persisten lactic acidosis
Respiratory problems
What does fumurate hydratase do?
Aka fumarase
Converts fumerate to malate
What is fumerase deficiency linked to?
Hereditary leiomyomatosis and renal cell cancer = HLRCC
