Chapter 9 Citric Acid Cycle (slide notes) Flashcards
for sugars with more than one chiral center, the D or L designiation refers to ___________
the assymetric carbon farthest from the aldehyde or keto group
D and L sugars are ________ of one another
mirror images
when is it an alpha anomer and when is it a beta anomer?
it is alpha when it is same side as OH . it is beta when it is the opposite. Note OH can b L (on left) or D (on right)
glycogen synthase is usually inactive when in the ______ form, and is usually active when in the __________ form
unactive phosphorylated b form
active in unphosphorlayted a form
insulin stimulates glycogen synthesis by ____________
inactivating glycogen sythase kinase
glycogen degradation in the livers is inhibited and glycogen sythesis is stimulated by high blood-glucose levels. The infusion of glucose into the blood stream leads to the inactivation of ________ followed by the activation of glycogen synthase in the liver
inactivation of phosphorylase1`
cellular respiration is the source of how much ATP??
90%
pyruvate is generated in the __________while the citric acid cycle occurs in the ___________
cytosol
mitochondria
define reduction potential
it is the tendency for a specific substance to gain electrons
Redox coenzyme:nicotinic acid:
universal electron carrier- NAD and NADP
dehydrogenases
Redox coenzyme:riboflavin (vitamen b2)
component of
-FMN and FAD
flavoproteins dyhydrogenase, oxidases, hydroxylases
it is a donor or acceptor of 2 H atoms
Coenzyme A is an __________
acyl carrier molecule
acetyl is derived from catabolism of _______,_______ and ________
carbohydrates, lipids, amino acids
pyruvate dehydrogenase complex, a mitochondrial matrix enzyme, oxidateively carboxylates pyruvate to form acetyl coA.
this reaction is _______ link between glycolysis and the citric acid cycle
irreversible
step 1 of decarboxylation:
________ a component of the complex, catalyzes the decarboxylation. Pyruvate combines with ionized form of the coenzyme thiamine pyrophosphate
step 2-oxidation
‘
the _________ is oxidized and transferred to dihydrolipoamide to form acetyllipoamide on E2 in a reaction also catalyzed by E1
step 3-formation of acetyl CoA
E2 catalyzes the transfer of the acetyl group from acetylipoamide to coenzyme A from acetly Coa
pyruvate dehydrogenase
two carbon fragment
dihydrolipoamide is formed by the attachment of the vitamen lipoic acid to a lysine residue in another enzyme in the complex ______________-
dihydrolipoyl transacetylase
to participate in another reaction in the cycle, dihydrolipoamide must be ______. this reaction is catalyzed by __________–
reoxidized
dihydrolipoamide dehydrogenase
the three enzymes of the pyruvate dehydrogenase complex are structurally integrated, and the __________ arm allows rapid movement of substartes and products from one active site of the complex to another
lipoamide arm
the formation of acetyl CoA from pyruvate is _____ in animal cells
irreversible
______________- catalyzes the condensation of acetyl CoA and oxaloacetate to form citrate
citrate synthase
oxaloacetate binding by ________ induces structural changes that lead to the formation of the acetyl coA binding site
citrate synthase
the formation of the reaction intermediate citry CoA causes a structural change that complese active site formation
citryl coA is cleaved to form citrate and coenzyme A
_____________- catalyzes the formation of isocitrate from citratte
acontitase
______________ catalyzes the oxidative decarboxylation of isocitrate, forming alpha-ketoglutarate and capturing high energy electrons as NADH
isocitrate dehydrogenase
alpha-ketoglutarate dehydrogenase complex =
catalyzes the synthesis of succinyl coA from alpha ketoglutarate, generating NADH
the enzyme and the reactions are structurally and mechanistically similar to the pyruvate dehydrogenase complex (E1-E3)
____________________- catalyzes the cleavage of a thioester linkage and concomitantly forms ATP
succinyl CoA synthetase (aka thiokinase)
__________,____________ and __________ catalyze successive reactions to regenerate oxaloacetate
succinate dehydrogenase, fumarase, malate dehydrogenase
what are irreversible enzyme in citric acid cycle and what are the positive / negative controls
pyruvate dehydrogenase
-ATP, acetyl CoA, and NADH
+ADP and pyruvate
isocitrate dehydrogenase
-ATP and NADH
+ADP
alpha-ketoglutarate dehydrogenase
-ATP, succiny, CoA, and NADH
because the citric acid cycle provides precursors for biosynthesis, reactions to replenish the cycle components are required if the energy status of the cell changes. These replenishing reactions are called ____________
anapleurotic reactions
