Exam 3

Question 2

E1 of pyruvate dehydrogenase

Answer 2

pyruvate dehydrogenase

Question 3

E2 of pyruvate dehyrdrogenase

Answer 3

dihydrolipoamide transacetylace

Question 4

E3 of pyruvate dehyrogenase

Answer 4

dihydrolipoamide dehydrogenase

Question 5

Five cofactors of pyruvate dehydrogenase (in order)

Answer 5

TPP, lipoamide, coenzyme A, FAD, NAD+

Question 6

Net outcome of PDH

Answer 6

2 electrons from pyruvate C-C bond transferred to NADH; acetyl group stored in acetyl-CoA via high energy thioester bond

Question 7

Step 1 of PDH

Answer 7

E1 (pyruvate dehydrogenase) decarboxylates pyruvate using TPP as a cofactor

Question 8

Step 2 of PDH

Answer 8

E2 (dihydrolipoamide transacetylace) transfers 2C from pyruvate onto lipoamide cofactor as an acetyl group

Question 9

Step 3 of PDH

Answer 9

E2 transfers acetyl group from acetyl dihydrolipoamide to coenzyme A (CoA)

Question 10

Step 4 of PDH

Answer 10

E3 (dihyrdolipoamide dehyrogenase) reoxidizes dihyrolipoamide to regenerate E2

Question 11

Step 5 of PDH

Answer 11

Transfer of 2e- to NAD+

Question 12

Active form of PDH

Answer 12

not phosphorylated

Question 13

Upregulates PDH phosphotase

Answer 13

Mg2+, Ca2+, insulin

Question 14

Upregulates PDH kinase

Answer 14

ATP, NADH, acetyl- CA

Question 15

Inhibits PDH kinase

Answer 15

pyruvate, ADP

Question 16

What’s produced by the citric acid cycle?

Answer 16

2 CO2, 1 GTP/ATP, 4 reduced electron carriers (carrying 4 pairs of electrons) per molecule of acetyl-CoA

Question 17

Enzyme in step 1 of CAC

Answer 17

Citrate synthase

Question 18

What does step 1 of CAC do

Answer 18

attaches acetate (2C) to oxaloacetate (4C) to form citrate (6C)

Question 19

enzyme in step 2 of CAC

Answer 19

Aconitase

Question 20

What does step 2 of CAC do

Answer 20

isomerizes citrate to isocitrate to set up the next step (energy harvesting)

Question 21

What is the importance of isocitrate?

Answer 21

Can be more easily oxidated than citrate

Question 22

Enzyme in step 3 of CAC

Answer 22

Isocitrate dehydrogenase

Question 23

What does step 3 of CAC do

Answer 23

catalyzes the first energy harvesting step

Question 24

What happens in an energy harvesting step?

Answer 24

2 electrons go to NAD+ as hydride (H+)

Question 25

Enzyme in step 4 of CAC

Answer 25

alpha-ketoglutamate dehyrdogenase

Question 26

What does step 4 of CAC do

Answer 26

catalyzes another energy-harvesting oxidative decarboxylation; back to 4C compound

Question 27

Enzyme in step 5 of CAC

Answer 27

Succinyl-CoA synthase

Question 28

What does step 5 of CAC do

Answer 28

uses the energy of succinyl-CoA to make an ATP/GTP

Question 29

Enzyme in step 6 of CAC

Answer 29

Succinate dehyrogenase

Question 30

What does step 6 of CAC do

Answer 30

oxidizes a C-C bond in succinate to an alkene, transferring 2 electrons to FAD

Question 31

Why is FAD needed in step 6 of CAC?

Answer 31

electrons are hard to pull out of succinate so FAD, stronger oxidizing agent than NAD+, is needed

Question 32

enzyme in step 7 of CAC

Answer 32

Fumerase

Question 33

What does step 7 of CAC do

Answer 33

stereospecifically oxidizes fumerate to malate

Question 34

Enzyme in step 8 of CAC

Answer 34

Malate dehydrogenase

Question 35

What does step 8 of CAC do

Answer 35

Oxidatively regenerates oxaloacetate

Question 36

Malate aspartate shuttle

Answer 36

exchanges cytosolic for mitochondrial NADH by running same reaction in opposite directions; does NOT result in lower ATP production

Question 37

Glycerophosphate shuttle

Answer 37

gets electrons from cytosolic NADH into ETC; loss of a bit of energy

Question 38

protonmotive force

Answer 38

electrochemical gradient of H+ across the inner membrane

Question 39

Soluble electron carriers in ETC

Answer 39

coenzyme Q (lipid), cytochrome c (membrane bound)

Question 40

Step 1 of ETC

Answer 40

Complex I uses energy from electrons stored in NADH to pump protons across inner mitochondrial membrane

Question 41

What are the entry points of electrons in complexes I and II?

Answer 41

FMN and FAD

Question 42

What do FMN/FAD do?

Answer 42

accept electrons either 1 or 2 at a time to convert 2 electron hydride transfers to 1 electron transfers to FeS clusters and Q

Question 43

Step 2 of ETC

Answer 43

Complex I transfers electrons (one at a time) to coenzyme Q

Question 44

Step 3 of ETC

Answer 44

Complex II (succinate dehydrogenase) uses FAD to extract 2e- from succinate then passes to Q

Question 45

Why is FAD needed for succinate?

Answer 45

succinate has a high affinity for e- and needs a stronger oxidizing agent

Question 46

What's different about the electrons that come from succinate in complex III?

Answer 46

these e- enter the ETC with less energy and don't drive proton pumping, so contribute less to ATP production

Question 47

Step 4 of ETC

Answer 47

Complex III uses "Q-cycle" to transfer 2e- one at a time from QH2 to cyt c, translocating H+

Question 48

What are cytochromes?

Answer 48

Heme containing proteins that use heme group to transfer e-

Question 49

Step 5 of ETC

Answer 49

Complex IV (cyt c oxidase) pumps 4 H+ out of matrix using energy of e- transfer from cytochrome c to oxygen

Question 50

What does the reduction of oxygen (by NADH) do?

Answer 50

provides energy to phosphorylate ADP

Question 51

What are the two sub-complexes of ATP synthase

Answer 51

Fo (transmembrane) and F1 complex

Question 52

Which subunits make up the rotor?

Answer 52

C ring and gamma, delta, epsilon, subunits

Question 53

Which subunits do not rotate

Answer 53

Stator + alpha/beta dimers (+a-subunit)

Question 54

What drives c ring rotation?

Answer 54

protonation and re-ionization of a glutamate in the c ring

Question 55

Which subunit drives conformational changes in the