ETC

Question 1

What is the outer mito membrane composed of? Is it permeable?

Answer 1

50% lipid and 50% protein; yes pretty much

Question 2

Inner mito membrane components? Permeable or impermeable?

Answer 2

80% protein/ 20 % lipid

impermeable

Question 3

What can you find in the mito matrix? (3 things)

Answer 3

enzymes of the CAC; the PDH complex, and enzymes for B-oxidation

Question 4

THE ETC is a series or chain of electron carriers in the inner mito membrane which funnels electrons from what to what?

Answer 4

reduced substrates such as NADH and succinate to oxygen

Question 5

What is the process of coupling oxidative metabolic substrates by the ETC to the phosphorylation of ADP to form ATP

Answer 5

oxidative phosphorylatin

Question 6

What are the 2 types of electron carriers involved in the ETC?

Answer 6

1. Proteins: dehydrogenases and iron-containing proteins, non-heme iron proteins
2. Lipids: CoQ

Question 7

What are 3 examples of reducing equivalents?

Answer 7

1. naked electrons
2. H atoms
   hydride ions

Question 8

What are the 4 major DHs? What do they use?

Answer 8

1. Succinate DH (FAD)
2. NADH dehydrogenase (FMN)
3. Fatty acyl-CoA DH (FAD)
4. Glycerol-3-Phos DH (FAD)

Question 9

What are the 2 types of iron-containing proteins?

Answer 9

1. cytochromes: heme-iron: Fe2+ (reduced form)

2. Non-heme iron: Fe-S: Fe2+ reduced

Question 10

What is the only non-iron electron carrier in the ETC?

Answer 10

coenzyme Q (ubiquinone)

Question 11

What are the 4 ETC enzyme complexes?

Answer 11

1. NADH-Coq Reductase:
   NADH + H+ CoQ –> NAD+ CoQH2
2. Succinate-CoQ Reductase
   Succinate + CoQ –> Fumarate + CoQH2
3. CoQH2-Cytochrome c Reductase
   CoQH2 + 2 cyc c (Fe3+) –> CoQ + 2 cyc c (Fe2+)
4. Cytochrome Oxidase
   4 cyc c (Fe2+) + 4H + O2 –> 4 cyc c (Fe3+) + 2H2O

Question 12

What are inhibitors of complex IV?

Answer 12

cyanide, CO

Question 13

Complex IV also contains what ion?

Answer 13

Cu.. fluctuates between CU2+ and Cu3+

Question 14

Where is the electrochemical gradient established in the ETC?

Answer 14

in the periplasmic space; generated by Com 1, 3, 4

Question 15

Describe the two subunits of ATP synthase?

Answer 15

F0: transmembrane proton channel
F1: makes ATP from ADP

Question 16

What are 2 uncouplers of the ETC?

Answer 16

DNP: inhibits formation of ATP but allows electron transport and proton pumping to still occur

Brown Fat:

Question 17

How does ATP actually get into the cytosol?

Answer 17

adenine nucleotide translocase, which exchanges ATP for ADP

Question 18

What is Atractyloside?

Answer 18

a specific inhibitor of adenine nucleotide translocase

Question 19

What can inhibit transport of ATP into the cytosol?

Answer 19

atractyloside

Question 20

How does MERFF result?

Answer 20

point mutation in the mitochondrial gene for lysine tRNA; cytochrome oxidase activity is diminished

Question 21

What results when there is a mutation causing a problem with cytochrome oxidase activity?

Answer 21

MERFF

Question 22

What is MELAS?

Answer 22

point mutation in leucine tRNA; cytochrome oxidase activity is near normal

Question 23

What is the difference between MERFF and MELAS?

Answer 23

cytochrome oxidase activity is reduced in MERFF, but cyc oxidase activity is basically normal in MELAS

Question 24

Poisoning by herbacides?

Answer 24

DNP: leads to hyperthermia due to uncoupling of oxidative phosphorylation witha resultant increase in heat production

treat with ice baths, oxygen, electrolytes

Question 25

Cyanide poisoning?

Answer 25

CN- inhibits cytochrome oxidase (complex 4); it reacts readily with heme group iron in the Fe3+ state; blocking reduction of oxygen to H20 causing lactic acidosis

Question 26

Treatment of cyanide poisoning?

Answer 26

nitrates or sodium thiosulfate

Question 27

CO?

Answer 27

stabilizes Hb in the R form; preventing release of 02 into the tissues; lactic acidosis