LEC TCA + Shuttle mechanisms Flashcards
Other names for citric acid cycle
Tricarboxylic acid cycle
Kreb’s cycle
TCA cycle
TCA is a major metabolic pathway involved in ____ (aerobic or anaerobic) metabolism
Aerobic
The term used when a pathway plays a role in both catabolism and anabolism
Amphibolic
T/F: TCA is amphibolic
T
Where does TCA take place?
Eukaryotes - mitochondrial matrix
Purpose of pyruvate oxidation in TCA
Prepare pyruvate for TCA cycle
End products of TCA
Acetyl-CoA, CO2, NADH+, H+
How many enzymes are involved in TCA?
5
Enumerate the steps in TCA cycle
- Condensation
- Isomerization
- Oxidation
- Oxidative decarboxylation
- Hydrolysis
- Oxidation
- Hydration
- Oxidation
- Repeat step 1
In the step 1 of TCA cycle, the ____ and ___ form ____ in the presence of ____
Acetyl-CoA; oxaloacetate; citrate; citrate synthase
The committed step in TCA cycle
Step 1: condensation where Acetyl-CoA an oxaloacetate form citrate in the presence of citrate synthase
In the step 2 of TCA cycle, ____ is isomerized to ____ in a 2-step reaction through _____
Citrate; isocitrate; aconitase
T/F: citrate is a chiral molecule
F
Intermediate forms in the step 2 of TCA cycle
cis-Aconitate
In the step 3 of TCA cycle, the ____ is oxidized to ____ through _____
Isocitrate; a-ketoglutarate; isocitrate dehydrogenase
The reaction in the step 3 of TCA cycle produces ____ and ____
CO2, NADH
In the step 4 of TCA cycle, ____ is oxidized through ____ and decarboxylated through ____ to produce ____ in the _____
a-ketoglutarate; NAD+; CoASH; Succinyl-CoA; a-ketoglutarate dehydrogenase complex
The reaction in the step 4 of TCA cycle produces _____ and _____
NADH, CO2
In the step 5 of TCA cycle, ____ is hydrolyzed to _____ with the enzyme _____
Succinyl-CoA; succinate; succinyl CoA synthetase
The first energy-yielding step in TCA
Step 5: hydrolysis where succinyl-CoA is hydrolyzed to succinate with succinyl CoA synthetase
In the step 5 of TCA cycle, ____ GTP molecule can be readily converted to ___ ATP molecule through ____
1; 1; nucleoside-diphosphate kinase (NDK)
In the step 6 of TCA cycle, ____ gets oxidized to fumarate through ____
Succinate; succinate dehydrogenase
In the step 7 of TCA cycle, ____ gets hydrated to ____ in the presence of ____ and ____
Fumarate; L-malate; H2O; fumarase
In the step 8 of TCA cycle, ____ is oxidized to ____ through _____
L-malate; oxaloacetate; malate dehydrogenase
The final reaction in TCA cycle produces ____
1 mole of NADH
The TCA cycle produces how many molecule of ATP, FADH2, and NADH?
1 molecule ATP
1 molecule FADH2
4 molecules NADH
Enumerate the three points of control within the TCA cycle
Citrate synthase
Isocitrate dehydrogenase
a-ketoglutarate dehydrogenase complex
Identify the point of control in TCA cycle: inhibited by ATP, NADH, and succinyl CoA
Citrate synthetase
Identify the point of control in TCA cycle: product of inhibition by citrate
Citrate synthetase
Identify the point of control in TCA cycle: activated by ADP and NAD+
Isocitrate dehydrogenase
Identify the point of control in TCA cycle: inhibited by ATP and NADH
Isocitrate dehydrogenase
Identify the point of control in TCA cycle: inhibited by ATP, NADH, and succinyl CoA
a-ketoglutarate dehydrogenase complex
Identify the point of control in TCA cycle: activated by ADP and NAD+
a-ketoglutarate dehydrogenase complex
The control point outside TCA cycle
Pyruvate dehydrogenase
Pyruvate dehydrogenase is inhibited by ___ and ____
ATP; NADH
Pyruvate dehydrogenase is a product inhibition by ____
Acetyl-CoA
Transport metabolites between mitochondria and cytosol
Shuttle mechanisms
Has been found in mammalian brains and muscles
Glycerol phosphate shuttle
T/F: NADH crosses the mitochondrial membrane; glycerol phosphate and dihydroxyacetone also crosses it
F; T
Through the glycerol phosphate shuttle, ___ ATP are produced in the ___ for each cytosolic NADH
1.5; mitochondria
Has been found in mammalian kidney, liver, and heart
Malate-Aspartate shuttle
T/F: malate and oxaloacetate crosses the mitochondrial membrane
F (only malate crosses)
What is produced in the transfer of electrons from NADH in the cytosol?
NADH in the mitochondria
In the malate-aspartate shuttle, ____mitochondrial ATP are produced for each cytosolic NADH
2.5
Mechanism that transfers electrons, but not NADH, from the cytosol across the mitochondrial membrance
Shuttle mechanisms
Electron transport is carried out by ____ closely related multi-subunit membrane-bound complexes and ___ electron carriers
4; 2
2 electron carriers in the electron transport chain
Coenzyme Q and cytochrome C
As a result of electron transport, protons are pumped across the ___ to the ____, creating a ____
Inner membrane; intermembrane space; pH gradient
What happens to the O2 in the electron transport chain?
O2 is reduced to H2O
