Chapter 19 - Exam 3

Question 1

Electron Transport Chain: Basics

Answer 1

ETC oxidizes NADH to NAD, passing electrons from one component to another
O2 + 4e- + 4H+ = 2H2O

Question 2

Where do the electrons come from?

Answer 2

come from NADH and FADH molecules produced during earlier stages of cellular respiration (glycolysis, pyruvate oxidation, and the citric acid cycle)

Question 3

What is the importance of oxygen?

Answer 3

oxygen is the final electron acceptor and forms water

Question 4

The components of the ETC.

Answer 4

1. NADH-Quinone Oxidoreductase
2. Succinate: Ubiquinone Oxidoreductase
3. Cytochrome b, cytochrome c1, ISP (iron sulfur protein)
4. Cytochrome c oxidase
5. Ubiquinone

Question 5

Complex 1

Answer 5

catalyzes two simultaneous and obligately coupled process
1. The exergonic transfer of a hydride ion from NADH and a proton from the matrix to ubiquinone
2. Proton transfer through the inner mitochondrial membrane

Question 6

Complex 2

Answer 6

FADH2 is oxidized by ubiquinone to reform FAD (couples the oxidation of succinate with the reduction of ubiquinone)…no proton pumping

Question 7

Complex 3

Answer 7

couples the transfer of 2 electrons from ubiquinol to cytochrome c with the vectorial transport of four protons to the intermembrane space
Net result: 2H+ are transferred to the intermembrane space from the matrix and cytochrome C is reduced

Question 8

Complex 4

Answer 8

carries electrons from cytochrome C to oxygen…oxygen accepts the electrons and pulls 4H+ from the matrix to form water (4 protons are pumped from the matrix to the intermembrane space)

Question 9

ATP Synthesis

Answer 9

oxidation/reduction reactions along the components of the ETC generate a proton gradient that is used by ATP synthase to phosphorylate ADP, producing ATP

Question 10

Describe the chemiosmotic model.

Answer 10

describes the coupling of ATP synthesis to an electrochemical proton gradient (proton-motive force)

Question 11

What are the two gradients that are maintained?

Answer 11

chemical potential and electrical potential gradients (forms a proton gradient in ETC)

Question 12

ATP Synthase.

Answer 12

a protein that can make a large amount of ATP
the proton gradient produced during the ETC is used to synthesize ATP…protons flow down the gradient into the matrix through ATP synthase, causing it to spin and catalyze the conversion of ADP to ATP

Question 13

Fo Subunit Structure and Function.

Answer 13

-an integral membrane protein with a proton pore
-embedded in the inner mitochondrial membrane; protons pass through the Fo transmembrane unit (acts as a mechanical driving device rotating the subunit F1, inducing conformational changes of F1)

Question 14

F1 Subunit Structure and Function.

Answer 14

-a peripheral membrane protein
-proton movement catalyzes the release of ATP by pumping protons across the membrane to create a proton gradient

Question 15

Conformational change in the B subunits catalyze ATP synthesis.

Answer 15

Binding-Change Model: B subunits have the ATP synthesis catalytic sites (B-ATP, B-ADP, B-empty); each complete rotation synthesizes three ATP

Question 16

Rotation of the gamma subunit (powered by proton movement) that causes the conformational change.

Answer 16

gamma subunit rotation causes a conformational change in the B subunits; ATP synthesis is catalyzed by the binding energy

Question 17

The rotation of the c ring on Fo powered by protons.

Answer 17

Rotational Catalysis: Mechanism by which the flow of protons through Fo causes the c ring to rotate and, in turn, trigger the subunit conformational changes in F1

Question 18

Understand in general how ATP, ADP and NADH regulate the various steps of ATP synthesis.

Answer 18

-breakdown of ATP increases ADP which in turn activates the processes which provide energy for ATP synthesis
-NADH is important as it is an electron carrier to the ETC and the oxidation of it can lead to the synthesis of 3 ATP
-ATP and ADP relative concentrations control the rates of electron transfer, oxidative phosphorylation, the citric acid cycle, pyruvate oxidation, and glycolysis