Respiratory chain and OxPhos

Question 1

Five classes of oxid/red centers

Answer 1

• Flavins
• FeS
• Q
• Cyt
• Cu

Question 2

Flavins as redox centers

Answer 2

• Two electron donor/acceptor
• 1,4 addition
• Ex: FMN of NADH dehydrogenase

Question 3

FeS redox centers

Answer 3

• Accept e’s from Flavins and Q
• 2 to 4 irons per center
• One electron donor/acceptor
• Ex: FeS center of complex III

Question 4

Ubiquinone (Q) redox centers

Answer 4

• Two electron donor/acceptor
• 1,6 addition
• Very hydrophobic–entirely embedded in membrane
• Cofactor
• Electron buffer

Question 5

Heme redox centers

Answer 5

• One electron donor/acceptors

- Ex: C heme of cytochromes c and c1

Question 6

Copper redox centers

Answer 6

• One electron donor/acceptors
• In cytochrome oxidase (complex 4)
• O2 binding site of respiratory chain

Question 7

ATP synthase structure

Answer 7

• F0F1
• F1 has three catalytic sites for ATP synthesis
• Connected to F0 by a central stalk and external stalk

-Will pump protons back inside the mitochondria to allow respiration to continue

Question 8

Overall rxn for oxphos

Answer 8

NADH+ H +0.5H20 + 3ADP + 3Pi –> NAD + 3ATP + 4H2O

Question 9

Respiratory control definition

Answer 9

• Endergonic synthesis of ATP is obligatorily coupled to exergonic redox reactions and vice versa
• Redox reactions may not proceed without ATP synthesis

Question 10

What causes respiratory control?

Answer 10

• Electrochemical gradient functions as a common intermediate linking oxidation to phosphorylation
• Rate of respiration is controlled by availability of ADP.

Question 11

Role of the transmembrane H+ gradient

Answer 11

• ATP synthesis
• Transport of ADP and ATP
• Heat
• Rotation of bacterial flagella
• Acidification of endomembrane compartments
• Transport of phosphate
• Antiports/symports/cations/sugars/AAs