Chapter 15: Oxidative Phosphorylation

The electron transport chain for oxidative phosphorylation sits in the [x] membrane of the [y] (eukaryotic organelle).

inner; mitochondria

Unlike glycolysis and the TCA cycle, oxidative phosphorylation is a purely [x] process.

catabolic

Why is the mitochondrial inner membrane extensively folded?

To increase surface area and oxidative phosphorylation.

What is the difference between carriers and co-factors?

While co-factors are tightly bound to enzymes, carriers circulate between distinct enzymes.

What is not a co-factor in the electron transport chain for oxidative phosphorylation?

plastoquinone

Order the following carriers from the electron transport chain for oxidative phosphorylation by reduction potential.

NADH → FADH₂ →ubiquinone (Q) → cytochrome c

[X] and [y] are among the several types of co-factors through which electron pass within the electron transport chain.

Any two of FAD, FMN, iron-sulfur clusters, heme-iron, flavin nucleotides, copper

The most commonly found metal in the various co-factors that make up the electron transport chain for oxidative phosphorylation of oxidative phosphorylation is [x].

iron

Both cytochrome c and complex IV of the electron transport chain for oxidative phosphorylation have heme-iron groups that serve as electron carriers, but that in [x] has higher affinity for electrons.

Complex IV

The heme-Fe in cytochrome c has [x] affinity for electrons than the FAD co-factor in complex II.

greater

Use of various co-factors enables [x] by the electron transport chain for oxidative phosphorylation.

stepwise transfer

Electrons are carried between the various complexes in the electron transport chain by [x] and [y].

ubiquinone (Q), cytochrome c

In the electron transport chain for oxidative phosphorylation, NADH is oxidized by [x].

Complex I

Complex I from the electron transport chain for oxidative phosphorylation is more accurately termed [x].

NADH:ubiquinone (Q) oxidoreductase

Complex I in the electron transport chain for oxidative phosphorylation oxidizes [x] and reduces [y].

NADH; ubiquinone (Q)

The protons added to ubiquinone (Q) by Complex I from the electron transport chain for oxidative phosphorylation come from the [x] in eukaryotes.

mitochondrial matrix

As part of its transfer of 2 electrons from NADH to ubiquinone (Q), Complex I from the electron transport chain for oxidative phosphorylation also moves [x] across the membrane.

4 protons

Complex I from the electron transport chain for oxidative phosphor

FMN, iron-sulfur clusters

Which complex in the electron transport chain for oxidative phosphorylation does not directly move protons across the membrane?

Complex II

Complex II is also known as [x].

succinate dehydrogenase

Complex II (succinate dehydrogenase) from the electron transport chain for oxidative phosphorylation contains an [x] co-factor through which electrons are transferred to ubiquinone (Q).

FAD

The protons added to ubiquinone (Q) by Complex II from the electron transport chain for oxidative phosphorylation come from the [x] in eukaryotes.

mitochondrial matrix

The only complex in the electron transport chain for oxidative phosphorylation that does not pump protons across the membrane is complex [x].

II

Succinate dehydrogenase from the TCA cycle is also known as [x] in the electron transport chain for oxidative phosphorylation and oxidizes carbon by increasing the number of bonds to [y].

complex II; carbon

The enzyme shared by the TCA cycle and electron transport chain for oxidative phosphorylation is [x].

succinate dehydrogenase (Complex II)

Which of the complexes in the electron transport chain for oxidative phosphorylation catalyzes the Q cycle?

complex III

Which state of ubiquinone (co-enzyme Q) is particularly important for proton movement across the membrane by complex III in the electron transport chain for oxidative phosphorylation?

semiquinone anion (•Q-)

Complex III from the electron transport chain for oxidative phosphorylation is more accurately termed [x].

ubiquinol (QH2):cytochrome c oxidoreductase

The semi-quinone anion state of ubiquinone (•Q-) is particularly important in complex [x] of the electron transport chain in oxidative phosphorylation.

III (3)

The half-reduced semiquinone (•Q-) state of ubiquinone is particularly important for proton pumping by [x] in the electron transport chain for oxidative phosphorylation.

Complex III

Cytochrome c as well as the cytochromes in Complex III (ubiquinol:cytochrome c oxidoreductase) from the electron transport chain for oxidative phosphorylation contain [x] co-factors.

heme-iron

Complex III (ubiquinol:cytochrome c oxidoreductase) from the electron transport chain for oxidative phosphorylation contains [x] and [y] co-factors.

heme-iron, iron-sulfur clusters

The Q cycle catalyzed by [x] in the electron transport chain for oxidative phosphorylation relies on the [y] state of Q to essentially move protons across the membrane.

complex III; semi-quinone (radical) anion (•Q-)

Complex III in the electron tra

Q-cylce

Complex IV from the electron transport chain for oxidative phosphorylation is more accurately termed [x].

cytochrome c oxidase

The key co-factors in Complex IV from the electron transport chain for oxidative phosphorylation are [x] and [y].

heme-iron, copper

As part of its transfer of 2 electrons from cytochrome c to molecular oxygen (O2), Complex IV from the electron transport chain for oxidative phosphorylation also pumps [x] across the membrane.

2 protons

The reduction of molecular oxygen (O₂) to 2 water molecules requires [x] (reduced) cytochromes c.

4

Match the complexes from electron transport chain for oxidative phosphorylation to their more functionally accurate names. NADH:Q oxidoreductase

Complex I

Match the complexes from electron transport chain for oxidative phosphorylation to their more functionally accurate names. Succinate dehydrogenase

Complex II

Match the complexes from electron transport chain for oxidative phosphorylation to their more functionally accurate names. QH2:cytochrome c oxidoreductase

Complex III

Match the complexes from electron transport chain for oxidative phosphorylation to their more functionally accurate names. cytochrome c oxidase

Complex IV

The electron transport chain in mitochondria create an [x], which is used to drive the formation of [y].

electrochemical gradient; high-energy phosphate bonds (~P)

The key residue in the c subunits of the c ring in ATP synthases is [x], as the protonated side-chain is not charged.

aspartate

The rotation of ATP synthases is driven by the interaction of aspartate or glutamate residues in the c ring with [x] in the a subunit, which enables the flow of protons across the membrane.

hemi-channels

The [x] (subunit) of the mitochondrial ATP synthase allows protons to flow down the electrochemical gradient.

c

The key aspartate in the subunits of the c ring in ATP synthases enables protons to move across the membrane because its side chain can exist in a [x] or [y] state.

protonated/unprotonated (charged/uncharged)

ATP synthase utilizes [x] force to form ~P (high-energy phosphate bonds).

mechanical (conformational, steric)

8 protons going through an ATP synthase that has 12 c subunits in its c ring produces [x] ATP (~P).

2

[X] ATP (~P) are produced by the ATP-synthase for each full (360°) rotation of its c sub-unit.

3

If an ATP synthase has [x] c subunits in its c ring, 4 protons are passed across the membrane per molecule of ATP formed.

12

If an ATP synthase has 9 c subunits in its c ring, [x] protons are passed across the membrane per molecule of ATP formed.

3

The import of inorganic phosphate (Pi) into the mitochondrial matrix is driven by the [x].

electrochemical gradient

The [x] drives the import of inorganic phosphate into the mitochondria.

electrochemical gradient

The import of ADP and export of ATP across the mitochondrial inner membrane is driven by the [x].

electrochemical gradient

The import of ADP and Pi as well as export of ATP uses ~[x]% of the electrochemical gradient across the mitochondrial inner membrane.

25

The electrochemical (proton) gradient across the inner mitochondrial membrane enables not only the synthesis of ATP, but also which of the following?

Import of ADP, Export of ATP, import of inorganic phosphate (Pi)

In oxidative phosphorylation electrons from NADH in the mitochondrial matrix generate more ATP than those from FADH2 because:

these go through complexes I, III & IV

In oxidative phosphorylation electrons from FADH2 generate less ATP than those from NADH because:

these go through complexes II, III & IV

Electrons from FADH2 generate less ATP than those from NADH because they are derived from oxidation of carbon by increasing the number of bonds to [x] instead of [y].

carbon; oxygen