Lecture 17

Question 1

Know the flow of electrons during respiration

Answer 1

Glucose → NADH → electron transport chain → oxygen

Question 2

the role of the electron transport chain in controlling the release of energy during oxidative phosphorylation

Answer 2

Passes electrons in a series of steps instead of one explosive reaction
O2 pulls electrons down the chain in an energy-yielding tumble
This energy is used to generate ATP

Question 3

the location of the electron transport chain and the multi-protein complexes that make up the chain

Answer 3

Location = inner membrane of the mitochondrion
Complexes
Complex I or II = electrons enter here depending on whether they enter as NADH or FADH2; sends electrons to Coenzyme Q
Complex III = receives electrons from CoQH2; transfers electrons to Cytochrome c
Complex IV = interacts with Cytochrome c after it is reduced
Transport of electrons in complexes I, III, and IV is coupled with the transport of protons across the inner membrane

Question 4

Know how the free energy of electrons change as they move through the electron transport chain and combine with the final electron acceptor, oxygen, to form water

Answer 4

Electrons drop in free energy as they go down the chain and are finally passed to O2, forming H2O

Question 5

Know the complexes to which NADH and FADH2 donate their electrons and describe the path these electrons take as they travel through the electron transport chain

Answer 5

NADH donates to complex I
FADH2 donates to complex II
Path of electrons
Complex I or II
Coenzyme Q transports electrons to Complex III (reduced to CoQH2)
Complex II transfers electrons to Cytochrome c
Cytochrome c accepts an electrons, it is reduced, diffuses in the membrane, and interacts with Complex IV

Question 6

Describe how oxidation and reduction relates to the movement of electrons through the electron transport chain

Answer 6

Energy is released as electrons are passed from NADH and FADH2 (high energy carriers) to O2 (low energy acceptor)
Released energy….
Reduces electrons carriers in the chain
Pumps protons into the intermembrane space via Complexes I, III, and IV

Question 7

Describe the role of protons in the electron transport chain including the region where they accumulate within the mitochondria

Answer 7

Proton concentration gradient contains high potential energy
Movement of protons is coupled with ATP synthesis
Protons flowing through the channel in the inner mitochondrial membrane make it possible for the ATP synthase enzyme to synthesize ATP
Protons accumulate in the mitochondrial matrix

Question 8

Describe the relationship between proton concentrations within the mitochondria and ATP Synthase

Answer 8

Two distinct subunits called F0 and F1
F0 forms the channel in the inner mitochondrial membrane through which protons flow. F1 is the catalytic unit that synthesizes ATP.

Question 9

Know the basic structure of ATP Synthase

Question 10

Describe how the movement of protons through ATP Synthase generates ATP

Answer 10

-Proton flow through the F0 channel causes it to rotate, converting the energy of the proton gradient into mechanical rotational energy, a form of kinetic energy
-The rotation of the F0 subunit leads to rotation of the F1 subunit in the mitochondrial matrix
-The rotation of the F1 subunit in turn causes conformational changes that allow it to catalyze the synthesis of ATP from ADP and Pi.