LEC TCA + Shuttle mechanisms

Question 1

Other names for citric acid cycle

Answer 1

Tricarboxylic acid cycle
Kreb’s cycle
TCA cycle

Question 2

TCA is a major metabolic pathway involved in ____ (aerobic or anaerobic) metabolism

Answer 2

Aerobic

Question 3

The term used when a pathway plays a role in both catabolism and anabolism

Answer 3

Amphibolic

Question 4

T/F: TCA is amphibolic

Answer 4

T

Question 5

Where does TCA take place?

Answer 5

Eukaryotes - mitochondrial matrix

Question 6

Purpose of pyruvate oxidation in TCA

Answer 6

Prepare pyruvate for TCA cycle

Question 7

End products of TCA

Answer 7

Acetyl-CoA, CO2, NADH+, H+

Question 8

How many enzymes are involved in TCA?

Answer 8

5

Question 9

Enumerate the steps in TCA cycle

Answer 9

1. Condensation
2. Isomerization
3. Oxidation
4. Oxidative decarboxylation
5. Hydrolysis
6. Oxidation
7. Hydration
8. Oxidation
9. Repeat step 1

Question 10

In the step 1 of TCA cycle, the ____ and ___ form ____ in the presence of ____

Answer 10

Acetyl-CoA; oxaloacetate; citrate; citrate synthase

Question 11

The committed step in TCA cycle

Answer 11

Step 1: condensation where Acetyl-CoA an oxaloacetate form citrate in the presence of citrate synthase

Question 12

In the step 2 of TCA cycle, ____ is isomerized to ____ in a 2-step reaction through _____

Answer 12

Citrate; isocitrate; aconitase

Question 13

T/F: citrate is a chiral molecule

Answer 13

F

Question 14

Intermediate forms in the step 2 of TCA cycle

Answer 14

cis-Aconitate

Question 15

In the step 3 of TCA cycle, the ____ is oxidized to ____ through _____

Answer 15

Isocitrate; a-ketoglutarate; isocitrate dehydrogenase

Question 16

The reaction in the step 3 of TCA cycle produces ____ and ____

Answer 16

CO2, NADH

Question 17

In the step 4 of TCA cycle, ____ is oxidized through ____ and decarboxylated through ____ to produce ____ in the _____

Answer 17

a-ketoglutarate; NAD+; CoASH; Succinyl-CoA; a-ketoglutarate dehydrogenase complex

Question 18

The reaction in the step 4 of TCA cycle produces _____ and _____

Answer 18

NADH, CO2

Question 19

In the step 5 of TCA cycle, ____ is hydrolyzed to _____ with the enzyme _____

Answer 19

Succinyl-CoA; succinate; succinyl CoA synthetase

Question 20

The first energy-yielding step in TCA

Answer 20

Step 5: hydrolysis where succinyl-CoA is hydrolyzed to succinate with succinyl CoA synthetase

Question 21

In the step 5 of TCA cycle, ____ GTP molecule can be readily converted to ___ ATP molecule through ____

Answer 21

1; 1; nucleoside-diphosphate kinase (NDK)

Question 22

In the step 6 of TCA cycle, ____ gets oxidized to fumarate through ____

Answer 22

Succinate; succinate dehydrogenase

Question 23

In the step 7 of TCA cycle, ____ gets hydrated to ____ in the presence of ____ and ____

Answer 23

Fumarate; L-malate; H2O; fumarase

Question 24

In the step 8 of TCA cycle, ____ is oxidized to ____ through _____

Answer 24

L-malate; oxaloacetate; malate dehydrogenase

Question 25

The final reaction in TCA cycle produces ____

Answer 25

1 mole of NADH

Question 26

The TCA cycle produces how many molecule of ATP, FADH2, and NADH?

Answer 26

1 molecule ATP
1 molecule FADH2
4 molecules NADH

Question 27

Enumerate the three points of control within the TCA cycle

Answer 27

Citrate synthase
Isocitrate dehydrogenase
a-ketoglutarate dehydrogenase complex

Question 28

Identify the point of control in TCA cycle: inhibited by ATP, NADH, and succinyl CoA

Answer 28

Citrate synthetase

Question 29

Identify the point of control in TCA cycle: product of inhibition by citrate

Answer 29

Citrate synthetase

Question 30

Identify the point of control in TCA cycle: activated by ADP and NAD+

Answer 30

Isocitrate dehydrogenase

Question 31

Identify the point of control in TCA cycle: inhibited by ATP and NADH

Answer 31

Isocitrate dehydrogenase

Question 32

Identify the point of control in TCA cycle: inhibited by ATP, NADH, and succinyl CoA

Answer 32

a-ketoglutarate dehydrogenase complex

Question 33

Identify the point of control in TCA cycle: activated by ADP and NAD+

Answer 33

a-ketoglutarate dehydrogenase complex

Question 34

The control point outside TCA cycle

Answer 34

Pyruvate dehydrogenase

Question 35

Pyruvate dehydrogenase is inhibited by ___ and ____

Answer 35

ATP; NADH

Question 36

Pyruvate dehydrogenase is a product inhibition by ____

Answer 36

Acetyl-CoA

Question 37

Transport metabolites between mitochondria and cytosol

Answer 37

Shuttle mechanisms

Question 38

Has been found in mammalian brains and muscles

Answer 38

Glycerol phosphate shuttle

Question 39

T/F: NADH crosses the mitochondrial membrane; glycerol phosphate and dihydroxyacetone also crosses it

Answer 39

F; T

Question 40

Through the glycerol phosphate shuttle, ___ ATP are produced in the ___ for each cytosolic NADH

Answer 40

1.5; mitochondria

Question 41

Has been found in mammalian kidney, liver, and heart

Answer 41

Malate-Aspartate shuttle

Question 42

T/F: malate and oxaloacetate crosses the mitochondrial membrane

Answer 42

F (only malate crosses)

Question 43

What is produced in the transfer of electrons from NADH in the cytosol?

Answer 43

NADH in the mitochondria

Question 44

In the malate-aspartate shuttle, ____mitochondrial ATP are produced for each cytosolic NADH

Answer 44

2.5

Question 45

Mechanism that transfers electrons, but not NADH, from the cytosol across the mitochondrial membrance

Answer 45

Shuttle mechanisms

Question 46

Electron transport is carried out by ____ closely related multi-subunit membrane-bound complexes and ___ electron carriers

Answer 46

4; 2

Question 47

2 electron carriers in the electron transport chain

Answer 47

Coenzyme Q and cytochrome C

Question 48

As a result of electron transport, protons are pumped across the ___ to the ____, creating a ____

Answer 48

Inner membrane; intermembrane space; pH gradient

Question 49

What happens to the O2 in the electron transport chain?

Answer 49

O2 is reduced to H2O