Citric Acid Cycle and Oxidative Phosphorylation

Question 1

Reason why TCA won’t occur anaerobically

Answer 1

NADH and FADH2 will accummulate (ETC is off)

Question 2

The ultimate fate of acetyl CoA in TCA

Answer 2

Oxidation to CO2

Question 3

Hormone that controls TCA activity

Answer 3

None. It happens irrespective of the fed or fasting state.

Question 4

Only TCA enzyme not found in the matrix of mitochondria

Answer 4

Succinate dehydrogenase (in the inner mitochondrial membrane)

Question 5

Major control enzyme in TCA, inhibited by NADH and ATP (high energy availability states) and activated by ADP

Answer 5

Isocitrate dehydrogenase

Question 6

TCA enzyme that requires thiamine-lipoic acid-CoA-FAD-NAD concoction like PDH

Answer 6

Alpha-ketoglutarate DH

Question 7

Catalyzes the substrate-level phosphorylation in TCA

Answer 7

Succinyl CoA synthetase (“synthetase” are enzymes catalyzing reactions that involve ATPs/GTPs, vs mere “synthases”)

Question 8

TCA enzyme that also functions in ETC

Answer 8

Succinyl DH, moonlights in ETC as “Complex II”

Question 9

Exit point in the TCA cycle for Fatty Acid Synthesis

Answer 9

Citrate via Citrate Shuttle

Question 10

Exit point in the TCA cycle for Heme Synthesis

Answer 10

Succinyl CoA

Question 11

Exit point in the TCA cycle for Gluconeogenesis

Answer 11

Malate via Malate Shuttle

Question 12

Entry point in the TCA cycle for Urea cycle

Answer 12

Fumarate

Question 13

Shuttle(s) of NADH to ETC (transport from cytoplasm to mitochondria)

Answer 13

Malate shuttle (3 ATP) and Glycerol phosphate shuttle (2 ATP)

Question 14

Shuttle(s) of FADH to ETC (transport from cytoplasm to mitochondria)

Answer 14

Glycerol phosphate shuttle (2 ATP)

Question 15

Final electron acceptor in the ETC

Answer 15

Oxygen

Question 16

Enzyme in Complex I of ETC

Answer 16

NADH Dehydrogenase

Question 17

Complex II of ETC

Answer 17

Coenzyme Q (a lipid)

Question 18

Complex III of ETC

Answer 18

Cytochrome b/c1 (an Fe/heme protein)

Question 19

Complex IV of ETC

Answer 19

Cytochrome a/a3 (a Cu/heme protein); Cytochrome oxidase is the enzyme involved

Question 20

Inhibitors of Complex I

Answer 20

Barbiturates, rotenone (Complex I has an enzyme, it is “inhibitable”)

Question 21

Inhibitors of Complex III (cyt b/c1)

Answer 21

Antimycin

Question 22

Inhibitors of Complex II (CoQ)

Answer 22

Doxorubicin

Question 23

Inhibitors of Complex IV

Answer 23

Cyanide, CO (Complex IV has an enzyme, it is “inhibitable”)

Question 24

Inhibitor of the F0F1 complex

Answer 24

Oligomycin (F1 has an enzyme, ATP synthase; it is “inhibitable”)

Question 25

Myocardial-specific creatine kinase

Answer 25

CK-MB (other markers that can be used: Trop I, Trop T, LDH)

Question 26

Headache, nausea, tachycardia, tachypnea, lips and cheeks turn a cherry-red color are caused by this ETC inhibitor

Answer 26

Carbon monoxide poisoning

Question 27

Term used for substances that decrease the proton gradient, which causes decreased ATP synthesis, increased oxygen consumption, and increased oxidation of NADH

Answer 27

Uncouplers, causing increase in rate of ETC without ATP synthesis, energy is released as heat (eg. 2,4-Dinitrophenol, high-dose aspirin and salicylates, thermogenin)

Question 28

Thermogenin is commonly known as _____, which protects newborns from hypothermia

Answer 28

“Brown fat”.

Question 29

Superoxide, hydrogen peroxide, and hydroxyl radical are collectively known as

Answer 29

Reactive oxygen species (produced by PMNs to kill bacteria by oxidative burst; also increased in reperfusion injury)

Question 30

MELAS

Answer 30

Mitochondrial encephalomyopathy, lactic acidosis, stroke-like episodes

Question 31

Leber hereditary optic neuropathy, MELAS, Ragged red muscle fiber disease are examples of

Answer 31

Mitochondrial DNA diseases (mutations)

Question 32

Rate of oxidative phosphorylation is dependent on

Answer 32

Availability of ADP (accummulation of ADP signals need for ATP synthesis; ADP also allosterically activates the rate controlling enzyme in TCA)

Question 33

Location of TCA

Answer 33

Mitochondria

Question 34

Inhibitor of the rate controlling enzyme of TCA

Answer 34

NADH inhibits isocitrate DH

Question 35

Location of ETC and Oxidative Phosphorylation

Answer 35

Mitochondrial inner membrane (Cell membrane in prokaryotes)

Question 36

Shuttle required for cholesterol and fatty acid synthesis in hepatocytes

Answer 36

Citrate shuttle

Question 37

Shuttle required for the hepatic conversion of pyruvate to glucose

Answer 37

Malate-aspartate shuttle

Question 38

High doses of nitroprusside inhibits what metabolic pathway

Answer 38

ETC. Cyt a/a3 (Complex IV) is inhibited by nitric oxide, plus metabolism of nitroprusside yields small quantities of cyanide

Question 39

Intracellular increases in AMP would increase activation in what enzyme

Answer 39

PFK-1