Chapter 19 (Citric Acid Cycle Regulation) Flashcards
Fatty acid synthesis requires ___ in the cytosol
Acetyl-CoA
Cytosolic acetyl-CoA is generated from the breakdown of ___
Citrate
Amino acid biosynthesis uses ___ and ___ as starting materials
alpha-ketoglutarate
oxaloacetate
Anaplerotic reaction know as ___ reactions
filling up
The ___ is essentially a source of free energy for aerobic organisms
Citric acid cycle
Pyruvate Decarboxylase
Anaplerotic Converts Pyruvate into OAA by adding a CO2 onto the last C Requires: ATP + CO2 Produces: ADP + Pi Irrevesible
Malic Enzyme
Anaplerotic Converts Pyruvate into L-Malate by adding a CO2 onto the last C and hydrolizing the keto group Requires: NADPH + H + CO2 Produces: NADP+ Reversible
3 Irreversible reactions of the TCA Cycle
Citrate Synthase
Isocitrate Synthase
Alpha-ketoglutarate Dehydrogenase
Pyruvate Dehydrogenase is regulated via product inhibition by ___ and ___
High concentration of NADH and Acetyl-CoA
Drive the reversible reactions of E2 and E3 backwards
TPP is trapped on the E1 in the hydroxyethyl form (because of the CO2)
PDH is covalently modified by phos/dephos of ___
E1
___ and ___ activate the enzyme ___ that phosphorylates ___ and inactivates it
NADH and Acetyl-CoA
pyruvate dehydrogenase kinase
E1
___ activates pyruvate dehydrogenase by activating ___
Ca 2+
pyruvate dehydrogenase synthase
Calcium simulates ___ and the production of ___
muscle contractions
ATP
Pyruvate Dehydrogenase regulation
Activates:
Inhibits:
Activates: NAD+ and CoA
Deactivates: Acetyl-CoA, NADH and ATP
The 3 irreversible steps of the TCA cycle are all deactivated by high concentrations of ___
NADH
When we slow down the TCA cycle we get a build up of ___ (which allosterically regulates ___)
citrate
PFK
Increased concentrations of ATP inhibits the enzymes ___ and ___
Citrate Synthase
Isocitrate Dehydrogenase
The three most important regulators of the TCA cycle are
Acetyl-CoA
OAA
NADH
An increase in Acetyl-Coa will pull the Malate Dehydrogenase reaction toward
OAA
The concentration of malate v. OAA depends fluctuates with
NADH/NAD concentrations
NADH + OAA
NAD + malate
The Glyoxylate Pathway is important for ___ and allows the bypass of ___ and gives us a net production of ___
growing seeds
CO2 producing steps
OAA
(mammals do not have this pathway)
