Exam (elaborations) Biochemistry CHAPTER 14

BIOCHEM CHAPTER 14 EXAM 14
For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle. -
CORRECT ANSWER-2

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric
acid cycle. - CORRECT ANSWER-6

In cellular respiration, most ATP molecules are produced by _____. - CORRECT
ANSWER-Oxidative phosphorylation

The final electron acceptor of cellular respiration is _____. - CORRECT ANSWER-
Oxygen

During electron transport, energy from _____ is used to pump hydrogen ions into the
_____. - CORRECT ANSWER-NADH and FADH2; intermembrane space

The proximate (immediate) source of energy for oxidative phosphorylation is _____. -
CORRECT ANSWER-Kinetic energy that is released as hydrogen ions diffuse down
their concentration gradient

The iron can gain or lose electron to move from ________ and ________ states. -
CORRECT ANSWER-Fe2+ and Fe3+

Which is a component of complex I?
(A) CoQ
(B) FMN
(C) FAD
(D) TPP - CORRECT ANSWER-(C) FAD

What is the role of FMN in complex I? - CORRECT ANSWER-Converts a two-electron
transfer to a one-electron transfer.

How many protons are translocated across the membrane by complex I for every pair of
electrons that are passed from NADH to CoQH2? - CORRECT ANSWER-4

The complete reaction catalyzed by complex I can be summarized as ________.
(A) NADH + Q +3H+ ↔ QH2 + NAD+ + 2H+
(B) NADH + Q +4H+ ↔ QH2 + NAD+ + 3H+
(C) NADH + Q ↔ QH + NAD+
(D) NADH + Q +5H+ ↔ QH2 + NAD+ + 4H+ - CORRECT ANSWER-(D) NADH + Q
+5H+ ↔ QH2 + NAD+ + 4H+

, Which complexes in the electron transport chain contribute to the pumping of protons in
to the intermembrane space? - CORRECT ANSWER-I, III, and IV

The terminal electron acceptor for complex III of the electron transport chain is
________. - CORRECT ANSWER-Cytochrome c

How many protons are pumped in to intermembrane space from matrix by complex III? -
CORRECT ANSWER-4

How many molecules of QH2 are oxidized and how many molecules of Q are reduced
respectively, during the Q cycle in complex III? - CORRECT ANSWER-2, 1

Which complex in the electron transport chain carries electrons from cytochrome c to
molecular oxygen, reducing it to water? - CORRECT ANSWER-IV

Overall, how many protons are pumped by the membrane-associated electron transport
system across the membrane for every molecule of NADH that is oxidized? -
CORRECT ANSWER-10

Arrange the sequence of electron transport through the mitochondrial respiratory
assembly in the correct order.
1. Coenzyme Q-cytochrome c reductase passes electrons to cytochrome c.
2. Coenzyme Q releases its electrons to complex III.
3. Cytochrome oxidase catalyzes the reduction of O2 to water.
4. Succinate, through complex II, and NADH, via complex I, release electrons to
coenzyme Q. - CORRECT ANSWER-4, 2, 1, 3

Arrange the sequence of events that occur in complex I in their proper order.
1. Fe+2 is oxidized to Fe+3 while Coenzyme Q is reduced to CoQH2
2. NADH is oxidized to NAD+ while FMN is reduced to FMNH2.
3. FMNH2 is oxidized while Fe+3 is reduced to Fe+2
4. Reduced CoQH2 is released. - CORRECT ANSWER-2, 3, 1, 4

Which statements about complex IV are true?
1. This complex catalyzes the reduction of oxygen to water.
2. Despite consuming protons, this complex pumps H+ across the membrane at a rate
of 4 per molecule of O2 reduced.
3. Protons flow down the gradient to the inner membrane space.
4. Conformational changes as electrons flow through the complex heme centers alter
the ability of some residues to bind protons. - CORRECT ANSWER-1, 2, and 4

Which of the four complexes pump protons out of the mitochondrial matrix? -
CORRECT ANSWER-Complexes I, III, and IV

Coenzyme Q carries electrons between which stages of the electron-transport chain? -
CORRECT ANSWER-- Complex I and III