In the mitochondria NADH and QH2 are essentially oxidized by ________ since it is the
terminal electron acceptor.
oxygen
The enzyme complexes associated with oxidative phosphorylation and the electron transport
chain can be classified as ________ proteins.
integral membrane
Which of the following substances can freely pass through the inner mitochondrial matrix?
CO2
In the respiratory electron transport chain electrons are passed from ________.
NADH and QH2 to O2
Compare the pH of the mitochondrial matrix and the inner membrane space.
The pH is lower in the inner membrane space.
The ________ is between the inner and outer membranes of the mitochondria
intermembrane space
Oxidative phosphorylation requires all of the items listed below
-ATP synthase in the correct position in the membrane.
-enzyme complexes embedded in a membrane.
- the flow of electrons from NADH and QH2 in the membrane.
-a terminal electron acceptor which is H2O in mitochondria.
ATP synthase is located in the ________ of the mitochondrion.
inner membrane
The inner membrane of mitochondria is permeable to ________, but not to ________.
uncharged molecules; charged molecules
The inner mitochondrial membrane contributes to the formation of a proton gradient mainly
because it
is a barrier to protons.
The chemiosmotic theory is a concept that ________.
a proton gradient that drives the formation of ATP
Which statement is true about two reactions that are coupled?
One reaction will normally not occur without the other.
In the presence of oxygen and in the absence of ADP, what occurs if the uncoupler
2,4-dinitrophenol is added to a suspension of normal mitochondria five minutes after an
oxidizable substrate has been added?
Oxidation of the substrate does not occur until the 2,4-dinitrophenol is added. Afterward,
oxidation proceeds rapidly until all of the substrate is consumed.
The protonmotive force is a result of ________.
a combination of an electrical potential and a chemical potential
At one time the uncoupler 2,4-dinitrophenol was used as a weight reducing drug. Its
side-effects, including death, resulted in its discontinued use. How could this drug cause
weight loss?
The uncoupler allows the oxidation of fats from adipose tissue without the production of
ATP. This allows the oxidation to proceed continuously and use up the fats.
For normal mitochondria in the presence of an oxidizable substrate and an uncoupler such as
2,4-dinitrophenol which do you expect?
- oxygen consumption even in the absence of ADP
- a rise in temperature to dissipate energy that would otherwise have been used to
generate ATP
- the flow of protons into the mitochondria matrix
The chemiosmotic theory explains
the source of energy for formation of mitochondrial ATP.
What feature of cytochromes makes them valuable in electron transport systems?
the iron ion
Which has the highest reduction potential?
O2
To reduce one molecule of O2, ________ electron(s) must be passed through the electron
transport chain and ________ molecule(s) of NADH is(are) oxidized.
4; 2
In a series of oxidation-reduction agents, the ________ reducing agent has the ________ reduction potential.
strongest; lowest
A lipid-soluble cofactor that can diffuse freely in the membrane of the electron transport chain
and carry electrons across the membrane is ________.
ubiquinone (Q)
Iron sulfur clusters (Fs-S) that can accept or donate one electron are found in which complexes
of the electron transport chain?
I, II and III
Which is a component of complex I?
FMN
What is the role of FMN in complex I?
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 QH2?
4
Which complex in the electron transport chain does not contribute to the proton gradient?
II
Which are components of complex II
Fe-S clusters
- FAD
- heme
The ultimate electron acceptor from complex II is ________.
Q
Which best describe the structure of complex II?
Three identical multisubunit enzymes that associate to form a mushroom-shaped
structure.
Complex II in the electron transport chain supplies electrons as ________ to the rest of the chain
(complexes III and IV).
QH2
The terminal electron acceptor for complex III of the electron transport chain is ________.
cytochrome c
How many protons are translocated across the inner mitochondrial membrane by complex III
for each pair of electrons passing through the electron transport chain?
4
During the Q-cycle ________ molecule(s) of QH2 is(are) oxidized and ________ molecule(s) of
Q is(are) produced.
2; 1
Which complex in the electron transport chain carries electrons from cytochrome c to molecular
oxygen, reducing it to water?
IV
Which statements is true about complex IV
-A binuclear center that contains an iron ion and heme-a3 is the site of the reduction of
molecular oxygen to water.
-The core structure of the cytochrome c oxidase in complex IV has three conserved
subunits.
- Copper ions shift from a +2 oxidation state
How many protons are translocated across the inner mitochondrial membrane by complex IV
for every pair of electrons passing through the electron transport chain?
2
The synthesis of one molecule of ATP from ADP requires ________ to be translocated across the
inner mitochondrial membrane.
Three protons
Rotation of the ________ subunit of ATP synthase causes conformational changes in the
catalytic sites that produce ATP.
g
Heat can be generated in the brown adipose tissue of hibernating mammals due to ________.
Uncoupling by themogenin
Which component of ATP synthase is the site of the proton channel?
F0
Which statement is true about the transport of ATP across the inner mitochondrial
membrane on its way to the cytosol?
- It is accomplished by adenine nucleotide translocase.
- The same enzyme that transports ATP also transport ADP in the opposite direction.
-The transport causes the loss of a net charge of -1 in the matrix.
The P/O ratio for passing electrons through complexes I, III and IV is ________.
2.5
The oxidation-reduction cofactor in the multisubunit enzyme fumarate reductase in E. coli
which has the greatest reduction potential is?
menaquinone.
The oxidizing agent in the enzyme superoxide dismutase is?
Copper
Superoxide dismutase protects cells from damage caused by ________.
�O2-