Electron Transport Chain

Question 1

How is energy stored in NADH and FADH2?

Answer 1

Thought their reduction potential

Question 2

How many of the subunits of complex one is coded for in the mitochondrial genome?

Answer 2

7, this means 7 of the 13 genes in mitochrodrial genome are used on this one protein

Question 3

How many ubiquinone sites are in complex I?

Answer 3

2, but only 1 comes off and transfers electrons to complex III

Question 4

Where are most of the redox centers in complex one found?

Answer 4

In the peripheral arm

Question 5

What is blocked by rotenone binding and where does it bind?

Answer 5

• Electron transfer from this complex is blocked

- Binds at one of the ubiquinone binding sites

Question 6

Which flavoproteins reduce ubiquinone in the ETC?

Answer 6

1. Complex I
2. Complex II
3. ETC-QO
4. NADH shuttle

Question 7

Why is it necessary that Flavin get electrons from NADH before they are given to Fe/S centers?

Answer 7

• NADH is an obligatory 2 electron donor
• Fe3+ is an obligatory 1 electron acceptor
• FMN can accept both electrons from NADH at the same time then transfer them one at a time to Fe3+

Question 8

T or F: an alteration in the mitochondrial genome has the potential to affect complex II.

Answer 8

False, complex II receives no coding from the mitochondrial genome

Question 9

How many protons does complex 2 contribute to the electron gradient?

Answer 9

NONE

Question 10

What side of complex 3 are the Rieske iron-sulfur protein and Cytochrom c1 found?

Answer 10

Found on the cytosolic (P -side)

Question 11

What does antimycin do to the ETC?

Answer 11

• Binds tightly to the N-center at the matrix side and prevent electrons from reaching ubiquinone from the b hemes

Question 12

What stigmatellin do to the ETC?

Answer 12

• binds at the P center at interface between Rieske and Cytochrome b
• Prevents QH2 from binding

Question 13

T or F: a defect in the mitochondrial genome could cause issues at complex IV

Answer 13

True - 3 of the subunits are coded for by the mitochondrial genome (these are the only 3 functional subunits)

Question 14

What is the idea of charge compensation?

Answer 14

• Adding a charge to the center of cytochrom c oxidase (complex IV) is thermodynamically expensive
• Taking up a proton to reduce the charge imbalance reduces the cost

Question 15

What accounts for the fact that complex IV acts as a proton pump?

Answer 15

Charge compensation, 4 electrons are taken in so 4 H+ are taken up

Question 16

Are both coppers at the copper A site required for functioning of complex IV.

Answer 16

Yes

Question 17

T or F: the protons that react with oxygen to form water in complex IV move through different routes than the pumped protons.

Answer 17

True