Oxidative Phosphorylation

Question 1

Is Oxidative Phosphorylation endergonic or exergonic?

Answer 1

Endergonic

Question 2

What drives oxidative phosphorylation?

Answer 2

Electron transport (the energy released from that is conserved through the endergonic synthesis of ATP by oxidative phosphorylation)

Question 3

What is the term for the way that oxidative phosphorylation (endergonic) is linked to electron transport to conserve the energy produced?

Answer 3

energy coupling

Question 4

What couples ATP synthesis to electron transport?

Answer 4

The transmembrane proton gradient generated by Complexes I, III, and IV of the electron transport chain.

Question 5

What enzyme catalyzes oxidative phosphorylation?

Answer 5

ATP synthase (sometimes called Complex I)

Question 6

What powers the synthesis of ATP?

Answer 6

The proton gradient created by electron transport.

Question 7

What is the chemiosmotic hypothesis?

Answer 7

Electron transport and ATP synthesis are coupled by a proton gradient across the inner mitochondrial membrane. Transporting electrons in the electron transport chain leads to pumping protons to the cytosolic side of the membrane, creating a lower H+ concentration on the matrix side of the membrane than on the cytosolic side. Protons then flow back into the matrix to equalize the distribution of protons, driving ATP synthesis (this is also called the proton motive force)

Question 8

What are the two components of the proton motive force?

Answer 8

1) A chemical gradient (pH)

2) A charge gradient (positive charge of protons)

Question 9

True or false: An intact proton-permeable membrane is required for the coupling of electron transport and oxidative phosphorylation.

Answer 9

True

Question 10

What supports the chemiosmotic (or proton motive) theory?

Answer 10

1) Intact, permeable mitochondral membrane is required for coupling.
2) The inner membrane is impermeable to ions.
3) Free diffusion of ions would discharge the electro-chemical gradient.

Question 11

True or false: Electron transport results in H+ transferred into the mitochondrial matrix.

Answer 11

False; electron transport transports H+ into the intermembrane space (increasing the pH and lowering the charge of the matrix).

Question 12

True or false: Increasing the acidity outside of the inner mitochondrial membrane stimulates ATP synthesis.

Answer 12

True

Question 13

What is the structure of ATP synthase?

Answer 13

Multisubunit transmembrane protein with two functional subunits, F0 and F1.

Question 14

Which of ATP’s synthases’subunits is a water-soluble peripheral membrane protein composed of at least 5 types of subunits?

Answer 14

F1

Question 15

Which of ATP synthases’s subunits is a water-insoluble transmembrane protein composed of at least 8 types of subunits?

Answer 15

F0

Question 16

What compound easily and reversible dissociates F0 and F1?

Answer 16

Urea

Question 17

True or false: F1 (water-soluble) synthesizes ATP.

Answer 17

False; it can hydrolyze ATP, but not synthesyze it.

Question 18

What connects the F1 peripheral membrane protein to the F0 transmembrane protein of ATP synthase?

Answer 18

a protein stalk (F1 looks like a lollipop).

Question 19

What are the three phases of ATP synthase’s production of ATP?

Answer 19

1) Translocation of protons by F1
2) F1 catalyzes formation of phosphoanhydride bond of ATP
3) F1 and F0 interaction that couples the dissipation of the proton gradient with ATP synthesis.

Question 20

How are F1 and F0 coupled?

Answer 20

By the gamma stalk that binds them.