Citric Acid Cycle (Deevska) Flashcards
3 names of Citric Acid Cycle
Krebs cycle, citric acid cycle, TCA cycle
Where does TCA cycle intersect with other metabolic pathways?
Catabolic pathways- breakdown of amino acids provides TCA cycle intermediates
Anabolic- some TCA intermediates feed into making other amino acids.
What provides most of the energy in the TCA cycle?
NADH and FADH2. These produce ATP through oxidative phosphorylation…
located in mitochondrial matrix very close to ETC…
List the steps of TCA cycle…
Pyruvate–Acetyl CoA+Oxaloacetate–Citrate–Isocitrate–Alpha-ketoglutarate–Succinyl CoA–Succinate– Fumarate–Malate–Oxaloacetate…
List the irreversible steps of TCA cycle…
- Acetyl CoA+Oxaloacetate to Citrate via Citrate synthase
- Isocitrate to Alpha-Ketoglutarate via Isocitrate Dehydrogenase
- alpha-ketoglutarate to Succinyl CoA via alpha-ketoglutarate dehydrogenase complex
What are the 5 different cofactors and what vitamin are they derived?
Thaimine pyrophosphate, TPP (from Thiamine, Vit B1)
Lipoamide (synthesized in human cells)
Coenzyme-A (CoA) (from pantothenic acid, vitamin B5)
FAD (from riboflavin, vitamin B2)
NAD+ (from nicotinamide, vitamin B3/niacin)
What 5 molecules activate PDH?
Pyruvate NAD+ ADP Ca2+ (muscle) CoA
What 3 molecules deactivate PDH?
Acetyl CoA
NaDH
ATP
What is the goal of steps 1,2,3, and 4?
Goal is to degrade Acetyl CoA…
Citrate is a feedback inhibitor of what?
PFK-1 Phosphofructokinase-1 used in glycolysis
Citrate is a precursor for ______ synthesis?
Fatty acid
What is the enzyme of isomeerization of citrate?
Aconitase… Works both directions.
What is the Rate Limiting step of TCA cycle?
Step 3… Oxidative phosphorylation of isocitrate. Yields the first NADH. Releases 1 CO2 and 1 C atom lost.
alpha ketoglutarate is also produced from what amino acid?
From the metabolism of glutamate.
Which step yields the second NADH releases 1 CO2?
alpha ketoglutarate to succinyl CoA via alpha ketoglutarate dehydrogenase complex.
