TCA cycle Flashcards
What is human respiration
Inhalation of oxygen from atmosphere; exhalation of CO2 and water
What is cellular respiration
Oxidation of acetate to CO2; reduction of O2 to H2O; this occurs in the mitochondria
Glucogenic aa enter the:
TCA cycle; they can go around the TCA cycle and go into oxaloacetate which is one of the starting point for gluconeogenesis
Ketogenic aa covert to
covert to acetyl CoA
What is the first stage of energy production
AcetylCoA can be produced f rom carbs, fats or proteins
What is the second stage of energy production
Generates reducing equivalents for electron transport in the form of NADH and FADH2
What is the third stage of energy production
Reducing equivalents generate a proton gradient used to drive ATP synthesis
The TCA cycle is _____; important in both anabolic and catabolic processes
amphibolic
PDH has 5 cofactors from 4 vitamins:
- Thiamine -TPP (vit B1)
- Riboflavin -FAD (vit B2)
- Niacin- NAD+ (vit B3)
- Panthothenate- Coenzyme A (Vitamin B5)
- Lipoate
pyruvate converts to acetyl CoA via
pyruvutae dehydrogenase
What are the enzymes that make up PDH
- E1: pyruvate dehydrogenase
- E2: Dihydrolipoyle Transacetylase
- E3: Dihydrolipoyle Dehydrogenase
Lipoate is a biological tether component of:
E2
E2 has functional domains conn by 20-30 aa linkers:
- NH2 terminal: lipoyl domain
- Central: E1 and E3 binding domain
- Inner core: acyltransferase domain
Aresenite complexes with ___
lipoate
Coenzyme is A is a component of
E2
FAD and NAD+ is a component of
E3
Riboflavin deficiency causes
angular cheilosis
Pyruvate dehydrogenase uses substrate _____
channeling;
What are the steps of pyruvate dehydrogenase
- Decarboxylate CO2 and transfer to thiamine which transfers to lipoalysine carrier form which becomes reduced after we attach the acetyl group to it.
- Transfers to coenzyme A molecule which bec released
- Make acetyl CoA
- regenerate enzyme to its active form. Lipolysine now needs to be reoxidized which happends through FAD.
- Now we reoxideze FAD to FADH via NAD
If our starting point are pyruvate and ____our end products are:
NAD+; acetyl CoA and NADH
How do we regulate pyruvate dehydrogenase
ATP and NADPH are signals to slow down Pyruvate dehydrogenase. Acetyl CoA is end product inhibitor.
What are the steps of the TCA cycle
- Condense carbons to oxaloacetate which condenses with acetyl CoA to make citrate
- Dehydrate/rehydrate via aconitase to make isocitrate
- Dehydrate carbons and rearrange to alpha ketoglutarate via isocitrate dehydrogenase
- Alpha kegolutarate dehydrogenase complex makes it lose another C02 and form succinyl CoA which has 4 carbons
- This converts to succinate where we get substrate level phosphorolation of GTP
- Make DB which makes fumerate and FADH2
- Hydrate DB to make malate
- Oxidize hydroxyl to make a keto –> oxaloacetate and NADH
Where does TCA cycle occur
Occurs in mitochondrial matrix
What are the end products
2 CO2’s
3 NADH’s
1 FADH2
1 GTP
What is substrate level phosphorolation
making ATP or GTP without using electron transport chain
4 dehydrogenase reactions yield
3 NADH and 1FADH2
First half steps of TCA are ____while second half is
irreversible; reversible
Aconitase has a ____center
Fe-S; important in iron metabolism
Which compounds downregulate the TCA cycle
ATP, NADH, citrate, succinylCoA
Which compounds upregulate TCA
ADP, Ca++
What is the glycerol phospahte shuttle
skeletal, muscle, brain; uses cytosolic and mitochondrial glycerol 3 P dehydrogenase
From alpha ketoglutarate we can get:
gluatamate–> argenin, proline, glutamine
Anapleurotic reactions replenish pathway intermediates ; most impt is the ____ which produces oxaloacetate
Pyruvate carboxylase
What are some TCA enzyme mutations
Fumerase: kidney and smooth muscle
Succinate dehydrogenase: adrenal gland; over produce epinephrine
-Both of these 2 build up and activates a transc factor: Hif1a (important in tumors, need new blood vessels to be made); stimulates glycolytic enzyme synthesis
