module 6- citric acid cycle

Question 1

where does the citric acid cycle occur?

Answer 1

mitochondria

Question 2

pyruvate must be transported into ( ) to be converted to ( ) so it can enter the citric acid cycle

Answer 2

mitochondria, acetyl CoA

Question 3

the pyruvate dehydrogenase complex contains ( ) enzymes and ( ) cofactors

Answer 3

3 enzymes, 5 cofactors

Question 4

how many of the 5 cofactors are derived from B vitamins?

Answer 4

4

Question 5

what type of reaction does the pyruvate dehydrogenase complex form?

Answer 5

oxidation decarboxylation

Question 6

what does oxidative reaction mean in terms of pyruvate?

Answer 6

pyruvate is oxidized and NAD is reduced to NADH which leads to ATP production

Question 7

what does decarboxylation reaction mean in terms of pyruvate?

Answer 7

forms acetyl CoA

3 carbon molecule to 2 carbon molecule

Question 8

what 2 pathways can acetyl CoA feed into?

Answer 8

citric acid cycle & fatty acid synthesis

Question 9

what is the benefit of having 3 enzymes in close proximity together like in the pryuvate dehydrogenase complex?

Answer 9

reaction rate increases

Question 10

what are the 2 ways the pyruvate dehydrogenase complex is regulated by?

Answer 10

covalent modification- phosphorylation of pyruvate dehydrogenase & post translational modification

allosterically

Question 11

what happens when pyruvate is dephosphorylated?

Answer 11

pyruvate dehydrogenase complex is reactivated

Question 12

signal for need of more energy = (phosphorylation/dephosphorylation ) = ( ) production of acetyl CoA

Answer 12

dephosphorylation, increased

Question 13

what type of health concern is produced when conversion of pyruvate -> acetyl CoA is reduced

Answer 13

cancer

Question 14

warburg effect

Answer 14

The feature of tumors to metabolize glucose to lactate instead of pyruvate, even in the presence of sufficient oxygen

Question 15

T or F: acetyl CoA enters CAC from other pathways not just pyruvate - why regulation is important

Answer 15

T

Question 16

what are the products of the CAC

Answer 16

3 NADH, 1 FADH2, 1 ATP, 1 CoA, 2 CO2, 2 H

Question 17

what are the 2 main regulatory enzymes of the CAC?

Answer 17

isocitrate dehydrogenase & a-ketoglutarate

Question 17

how are the 2 regulatory enzymes regulated?

Answer 17

allosterically

Question 18

T or F: CAC occurs only under aerobic conditions but there is no O2 requirement

Answer 18

T

Question 19

what is the rate of acetyl CoA from pyruvate controlled by?

Answer 19

level of pyruvate dehydrogenase

Question 20

what is the major goal of the CAC

Answer 20

oxidize acetyl CoA for ATP generation - produce energy

Question 21

NADH & ATP reflect (high/low) energy state & (inhibits/activates) isocitrate dehydrogenase

Answer 21

high, inhibits

Question 22

ADP reflects (high/low) energy state & (inhibits/activates) isocitrate dehydrogenase

Answer 22

low, activates

Question 23

what 3 things is a-ketaglutarate dehydrogenase is inhibited by?

Answer 23

ATP, NADH & succinyl CoA

Question 24

isocitrate dehydrogenase inhibited = levels of citrate ( ) = ( ) PFK

Answer 24

increase, inhibit

Question 25

increase in a-ketoglutarate occurs when a-ketoglutarate dehydrogenase is ( )

Answer 25

inhibited

Question 26

T or F: CAC provides intermediates for biosynthesis of other biomolecules

Answer 26

T

Question 27

Anapldrotic reactions

Answer 27

reactions that replenish intermediates of CAC

Question 28

what reaction in the CAC is an anapldrotic reaction? what enzyme catalyzes this?

Answer 28

pyruvate -> oxaloacetate enzyme: pyruvate decarboxylase

Question 29

glyoxylate cycle

Answer 29

allows plants to synthesize glucose & carbs from fat- mammals can't do this

Question 30

high energy electrons are usually captured in the form of which molecules?

Answer 30

NADH & FADH2

Question 31

how many CO2 molecules are produced during 1 round of CAC

Answer 31

2

Question 32

how many ATP do NADH generates & how many does FADH2 generate?

Answer 32

NADH- 2.5 ATP FADH2- 1.5 ATP

Question 33

how many ATP are generated after 1 round of the CAC?

Answer 33

10 ATP

Question 34

T or F: in the absence of O2, NAD & FAD can be regenerated

Answer 34

F, they cannot be without O2

Question 35

how does the glyoxylate cycle differ from the CAC?

Answer 35

2 acetyl CoA enter instead of 1

Question 36

what 2 enzymes are in glyoxylate cycle but not CAC?

Answer 36

isocitrate lyase & malate synthase

Question 37

ATP, NADH & succinyl CoA ( ) a-ketoglutarate

Answer 37

inhibit

Question 38

increase in citrate ( ) isocitrate dehydrogenase = ( ) PFK

Answer 38

inhibits, inhibits