Quiz 1 (Bioenergetics) Flashcards
The TCA cycle is an ___ pathway and takes place in the ___.
amphibolic / mitochondria
*both catabolic and anabolic
What enzyme allows pyruvate to enter the mitochondrial matrix?
What enzyme splits pyruvate into acetyl-CoA?
Mitochondrial Pyruvate Carrier (MPC)
Pyruvate Dehydrogenase (PDC)
PDC produces…
1 NADH / 1 carbon dioxide / 1 acetylene-CoA
What enzyme links glycolysis to the TCA Cycle?
Pyruvate Dehydrogenase Complex (PDC)
PDC is made of:
3 enzymes (E1 / E2 / E3)
+
5 coenzymes (TPP / CoA / Lipoic Acid / FAD / NAD+)
- TPP is derived from Vitamin B1
- FAD is derived from Vitamin B2
- NAD+ is derived from Vitamin B3
- CoA is derived from Vitamin B5
Phosphorylation of the PDC occurs in coenzyme ____ of the enzyme ___.
Thiamine Pyrophosphate (TPP)
E1
PDC regulation:
Pyruvate Dehydrogenase Kinase (PDK) =>
+Po = inactive PDC
Pyruvate Dehydrogenase Phosphatase (PDP) =>
-Po = ACTIVE PDC
- insulin activates PDK
- activators = Calcium / Magnesium / ADP / CoA / NAD+ / pyruvate
- inhibitors = Acetyl-CoA / NADH / ATP / Arsenite
When ___ phosphorylates PDC, PDC will become ___.
PDK / inactive
What 3 enzymes are associated with highly regulates steps in the TCA cycle?
Citrate Synthase
Isocitrate Dehydrogenase
Alpha-ketoglutarate Dehydrogenase
What enzyme is responsible for generation of an ATP equivalent in the TCA cycle?
Succinate Thiokinase
*generates GTP
What enzyme produces FADH2 in the TCA cycle?
Succinate Dehydrogenase (aka. Complex II of ETC)
When the cellular ATP levels are low, the activity of the TCA cycle is ___.
Increased
___ reaction replenish intermediates of the TCA cycle.
Examples
Anaplerotic
- FED: Pyruvate —> OAA
- FASTING: Asn —> Asp —> OAA
- FASTING: Gln / Pro / His / Arg —> Glu —> alpha-ketoglutarate
- FASTING: Thr / Met / Ile / Val —> Propionyl CoA —> Succinyl CoA
- FASTING: Phe / Tyr / Asp —> Fumarate
___ inhibits Pyruvate Carboxylase from converting Pyruvate into OAA.
Insulin
Oncometabolites of the TCA cycle include ___ and ___.
Citrate
2-hydroxyl glutarate
OxPhos takes place in the ___.
Inner-mitochondrial membrane
Goals of OxPhos:
- Transfer electrons (from NADH/FADH2 to oxygen)
- Establish a proton gradient
- Synthesize ATP
Proton motive force is made by:
- pH gradient (Direction of H+ flow)
2. Membrane potential (“non-leakiness” of membrane)
___ inhibits ATPase by disrupting the proton transport through the channel.
Oligomycin
1 mol ATP requires passage of ____ H+.
3+1
___ is the only ETC complex that does not pump protons across the innermembrane.
Complex II
___ transfers electron to molecular oxygen.
Complex IV
Inhibition of electron transfer down the ETC causes a ___ in the pumping of protons.
Decrease
OxPhos is sensitive to ___ and ___.
Oxygen
[ATP/ADP] ratio
____ disrupts the proton gradient and causes heat production instead of ATP synthesis.
Uncoupling (proton leak)
DNP is an _____ that disrupts the proton gradient, thereby causing a ___ in ATP synthesis.
Uncoupling agent / decrease
Shuttles are important because ____ cannot enter the mitochondria on its own.
NADH
Malate-Aspartate Shuttle
Vs.
Glycerophosphate Shuttle
Malate-Aspartate Shuttle
- occurs in heart / liver / kidney
- NADH is shuttled into the mitochondrial matrix
- NADH enters ETC at Complex I
- reversible (depends on the fact that OAA cannot pass membranes)
Glycerophosphate Shuttle
- occurs in muscle and brain
- electrons from FADH2 are shuttled into CoQ
- irreversible
