7.5 The Electron Transport Chain and Oxidative Phosphorylation

Question 1

the complete oxidation of glucose during the first three stages of cellular respiration results in the production of:

Answer 1

two kinds of reduced electron carriers: NADH and FADH2

Question 2

the energy in electron carriers is released in a series of:

Answer 2

redox reactions that occur as electrons pass through a chain of protein complexes in the inner mitochondrial membrane to the final electron acceptor, oxygen, which is reduced to water

Question 3

the passage of electrons is coupled to the transfer of protons across the inner mitochondrial membrane creating:

Answer 3

a concentration and charge gradient: this electrochemical gradient provides a source of potential energy that is used to drive the synthesis of ATP

Question 4

the inner mitochondrial membrane is:

Answer 4

selectively permeable (Protons can’t passively diffuse across, other molecules’ movement controlled by transporters and channels)

Question 5

what are the two components of a proton gradient?

Answer 5

chemical-difference in concentration, electrical-difference in charge =e electrochemical gradient

Question 6

the proton gradient is a source of:

Answer 6

potential energy

Question 7

ATP synthase

Answer 7

an enzyme that couples the movement of protons through the enzyme with the synthesis of ATP

Question 8

the gradient of protons provides a source of potential energy that is converted into:

Answer 8

chemical energy stored in ATP

Question 9

chemiosmotic hypothesis

Answer 9

the hypothesis that the gradient of protons across a membrane provides a source of potential energy that is converted into chemical energy stored in ATP

Question 10

where do electrons enter the electron transport chain?

Answer 10

at complex I (NADH) or complex II (FADH2)

Question 11

the transport of electrons in complex I, III, and IV is coupled with:

Answer 11

the transport of protons across the inner membrane, from the mitochondrial matrix to the intermembrane space

Question 12

within each protein complex of the electron transport chain, electrons are passed from:

Answer 12

electron donors to electron acceptors

Question 13

each electron donor and acceptor is a:

Answer 13

redox couple, consisting of an oxidized and a reduced form of a molecule

Question 14

the final reduction of oxygen to water is catalyzed by which complex?

Answer 14

complex IV

Question 15

coenzyme Q (CoQ) AKA ubiquinone (hydrophobic)

Answer 15

in respiration, a mobile electron acceptor that transports electrons from complies I and II to complex III in the electron transport chain and moves protons from the mitochondrial matrix to the intermembrane space

Question 16

once two electrons and two protons are transferred to CoQ, it forms:

Answer 16

CoQH2

Question 17

cytochrome c (hydrophilic)

Answer 17

the enzyme to which electrons are transferred in complex III of the electron transport chain

Question 18

once electrons are transferred from CoQH2 to cytochrome c, what happens to the protons?

Answer 18

they are released into the intermembrane space

Question 19

the electron transfer steps are associated with the release of energy as electrons are passed from the reduced electron carriers (NADH, FADH2) to the final electron acceptor O2

Answer 19

some of the energy is used to reduce the next carrier, some used to pump protons across the inner mitochondrial membrane

Question 20

the result of transfer of electrons being coupled with the pumping of protons is an:

Answer 20

accumulation of protons in the intermembrane space

Question 21

where are protons in higher concentration?

Answer 21

in the intermembrane space, low concentration in the mitochondrial matrix. protons can’t diffuse into matrix because membrane blocks it, the gradient stores potential energy

Question 22

the oxidation of the electron carriers NADH and FADH2 which formed during glycolysis, pyruvate oxidation, and the citric acid cycle leads to:

Answer 22

the generation of a proton electrochemical gradient (a source of potential energy) which is used to synthesize ATP

Question 23

the ATP synthase enzyme is composed of two distinct subunits called:

Answer 23

F0 and F1

Question 24

Fo forms the:

inner mitochondrial membrane

Answer 24

channel in the inner mitochondrial membrane through which protons flow, rotates as protons pass through

Question 25

F1 is the :

mitochondrial matrix

Answer 25

catalytic unit that synthesizes ATP, uses rotational energy of Fo to synthesize ATP

Question 26

proton flow through the Fo channel causes it to rotate, converting the energy of the proton gradient into:

Answer 26

mechanical rotational energy (kinetic energy), leads to the rotation of the F1 subunit in the mitochondrial matrix

Question 27

the rotation of the F1 subunit causes:

Answer 27

conformational changes that allow it to catalyze the synthesis of ATP from ADP and Pi, converting mechanical energy into the chemical energy of ATP

Question 28

what are sufficient components to produce ATP?

Answer 28

a membrane, proton gradient, and ATP synthase

Question 29

for each molecule of NADH that donates electrons, how many ATP are produced?

Answer 29

2.5 molecules

Question 30

for each molecule of FADH2 that donates electrons, how many ATP are produced?

Answer 30

1.5 molecules

Question 31

overall, the complete oxidation of glucose yields how many ATP?

Answer 31

32