Electron transport chain

Question 1

Step 1

Answer 1

Complex 1 picks up high energy electrons from NADH and conducts them through flavin-mononucleotide and an iron-sulfur protein to ubiquinone

Question 2

Step 2

Answer 2

Complex 2 oxidizes FADH to FAD, and the two electrons released are transferred to ubiquinone, and the two protons released go into the matrix.

Question 3

Step 3

Answer 3

Complex 3 accepts electrons from ubiquinone and transfers them through the electron carriers cytochrome b (an iron-sulfur protein) and cytochrome c1 to cytochrome c, which is in the intermembrane space

Question 4

Step 4

Answer 4

Complex 4 accepts electrons from cytochrome c and delivers them via cytochromes a and a3 to oxygen, where four protons are added to O2 to make 2 H2O

Question 5

Step 5

Answer 5

As electrons move through the electron transfer system, they release free energy, part of which is lost as heat. Some is used by the mitochondrion to transport H+ into the inner membrane compartment

Question 6

Which complexes pump H+ into the inner membrane compartment?

Answer 6

1,3,4

Question 7

Step 6

Answer 7

Resulting H+ gradient supplies energy source for ATP synthase, because H+ flows through a channel in atp synthase, making the headpiece and stalk rotate, causing the headpiece to catalyze ATP synthesis

Question 8

Where is the basal unit of ATP synthase located?

Answer 8

In the membrane

Question 9

Where can complex II be found?

Answer 9

Bound to the inner mitochondrial membrane on the matrix side

Question 10

What are cytochromes?

Answer 10

Proteins with a heme prosthetic group that contains an iron atom that accepts and donates electrons