Chapter 9 Citric Acid Cycle (slide notes)

Question 1

for sugars with more than one chiral center, the D or L designiation refers to ___________

Answer 1

the assymetric carbon farthest from the aldehyde or keto group

Question 2

D and L sugars are ________ of one another

Answer 2

mirror images

Question 3

when is it an alpha anomer and when is it a beta anomer?

Answer 3

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)

Question 4

glycogen synthase is usually inactive when in the ______ form, and is usually active when in the __________ form

Answer 4

unactive phosphorylated b form

active in unphosphorlayted a form

Question 5

insulin stimulates glycogen synthesis by ____________

Answer 5

inactivating glycogen sythase kinase

Question 6

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

Answer 6

inactivation of phosphorylase1`

Question 7

cellular respiration is the source of how much ATP??

Answer 7

90%

Question 8

pyruvate is generated in the __________while the citric acid cycle occurs in the ___________

Answer 8

cytosol

mitochondria

Question 9

define reduction potential

Answer 9

it is the tendency for a specific substance to gain electrons

Question 10

Redox coenzyme:nicotinic acid:

Answer 10

universal electron carrier- NAD and NADP

dehydrogenases

Question 11

Redox coenzyme:riboflavin (vitamen b2)

Answer 11

component of
-FMN and FAD

flavoproteins dyhydrogenase, oxidases, hydroxylases

it is a donor or acceptor of 2 H atoms

Question 12

Coenzyme A is an __________

Answer 12

acyl carrier molecule

Question 13

acetyl is derived from catabolism of _______,_______ and ________

Answer 13

carbohydrates, lipids, amino acids

Question 14

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

Answer 14

irreversible

Question 15

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

Answer 15

pyruvate dehydrogenase

two carbon fragment

Question 16

dihydrolipoamide is formed by the attachment of the vitamen lipoic acid to a lysine residue in another enzyme in the complex ______________-

Answer 16

dihydrolipoyl transacetylase

Question 17

to participate in another reaction in the cycle, dihydrolipoamide must be ______. this reaction is catalyzed by __________–

Answer 17

reoxidized

dihydrolipoamide dehydrogenase

Question 18

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

Answer 18

lipoamide arm

Question 19

the formation of acetyl CoA from pyruvate is _____ in animal cells

Answer 19

irreversible

Question 20

______________- catalyzes the condensation of acetyl CoA and oxaloacetate to form citrate

Answer 20

citrate synthase

Question 21

oxaloacetate binding by ________ induces structural changes that lead to the formation of the acetyl coA binding site

Answer 21

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

Question 22

_____________- catalyzes the formation of isocitrate from citratte

Answer 22

acontitase

Question 23

______________ catalyzes the oxidative decarboxylation of isocitrate, forming alpha-ketoglutarate and capturing high energy electrons as NADH

Answer 23

isocitrate dehydrogenase

Question 24

alpha-ketoglutarate dehydrogenase complex =

Answer 24

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)

Question 25

____________________- catalyzes the cleavage of a thioester linkage and concomitantly forms ATP

Answer 25

succinyl CoA synthetase (aka thiokinase)

Question 26

__________,____________ and __________ catalyze successive reactions to regenerate oxaloacetate

Answer 26

succinate dehydrogenase, fumarase, malate dehydrogenase

Question 27

what are irreversible enzyme in citric acid cycle and what are the positive / negative controls

Answer 27

pyruvate dehydrogenase
-ATP, acetyl CoA, and NADH
+ADP and pyruvate

isocitrate dehydrogenase
-ATP and NADH
+ADP

alpha-ketoglutarate dehydrogenase
-ATP, succiny, CoA, and NADH

Question 28

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 ____________

Answer 28

anapleurotic reactions