BIOCHEM Chp.10 TCA, ETC, & Oxidative Phosphorylation Flashcards
What are the steps of the TCA?
- Pyruvate → A-CoA via PDH
- A-coA → Citrate (OOA + A-CoA) via Citrate Synthase
- Citrate → Isocitrate via cis-Aconitate
- Isocitrate → alpha-Ketoglutarate via Isocitrate DH
- A-ketoglutarate → Succinyl-CoA via alpha-ketoglutarate DH
- Succinyl-CoA → Succinate via Succinyl-CoA Synthetase
- Succinate → Fumarate via Succinate DH
- Fumarate → Malate via Fumarase
- Malate → OOA via Malate DH
- OOA → A-CoA via Citrate Synthase
Where do the TCA, ETC, Glycolysis, and oxidative phosphorylation occur?
TCA/Kreb’s cycle - mitochondrial matrix
Oxidative phosphorylation - inner mitochondrial membrane
ETC - inner mitochondrial membrane
Glycolysis - cytosol
ATP Phosphorylation - cytosol and mitochondria
What are the main functions of TCA?
Oxidation of aCoA to CO2, water, GTP, NADH, FADH2
What are the 5 enzymes of the PDH?
- Pyruvate dehydrogenase
- Dihydrolipoyl transacetylase
- Dihydrolipoyl dehydrogenase
- Pyruvate dehydrogenase kinase
- Pyruvate dehydrogenase phosphatase
What inhibits the PDH?
accumulation of aCoA and NADPH
What is B-oxidation?
the use of FA to form aCoA.
What is the overall reaction of the PDH complex
pyruvate + CoA-SH + NAD+ –> a-CoA + CO2 + NADH + H+
What do dehydrogenases do?
transfer hydride ion (H-) to an electron acceptor, usually NAD+ or FAD
What is the diff b/w succinyl-CoA synthetase and citrate synthase?
citrate synthase doesn’t require energy input to form a solvent bond, but succinyl-CoA synthetase does
How much ATP is generated in glycolysis and TCA?
glycolysis: 7
TCA: 25
What activates and inhibits the PDH Complex?
PDH Kinase is activated by high ATP levels which has an inhibitory effect on the PDH Complex.
On the other hand, PDH Phosphatase is activated by high ADP levels and activates the PDH complex
What inhibits Citrate Synthase?
inhibited by ATP, NADH, S-Co-A, and citrate
What inhibits and activates Isocitrate DH?
ADP and NAD* are activators,
ATP and NADH are deactivators
What inhibits and activates a-KGDH?
ADP, NAD+, and Calcium are activators.
ATP, NADH, and S-Co-A are deactivators
What is the diff b/w aerobic and anaerobic respiration?
Aerobic respiration occurs in the mitochondria, while anaerobic respiration and fermentation occur in the cytosol
What is the purpose of the ETC?
The movement of protons from the mitochondrial matrix to the inner mitochondrial membrane space creates a greater concentration gradient of hydrogen ions that can be used to drive ATP Synthesis
What is the function of pyruvate dehydrogenase?
it oxidizes pyruvate, creating CO2; it requires thiamine pyrophosphate (vit B1/TPP) and Mg2+
What is the function of dihydrolipoyl transacetylase?
it oxidizes the remaining 2-carbon from TPP molecule using lipoic acid and transfers the resulting acetyl group to CoA forming aCoA
What is the function of Dihydrolipoyl dehydrogenase?
it used FAD to re-oxidize lipoic acid, forming FADH2. This FADH2 can later transfer electrons to NAD+ forming NADH that can feed into the ETC
What is the function of Pyruvate dehydrogenase kinase?
it phosphorylates PDH when ATP or aCoA levels are high, turning it off