Explain the difference between oxidative phosphorylation and
substrate level phosphorylation?
Substrate-level phosphorylation occurs during Glycolysis and the
Kreb's Cycle and involves the physical addition of a free
phosphate to ADP to form ATP. Oxidative phosphorylation, on the
other hand, takes place along the electron transport chain,
where ATP is synthesized indirectly from the creation of a proton
gradient and the movement of these protons back accross the
membrane through the protein channel, ATP synthase. As the
protons pass through, ATP is created.
Explain the roles of cytochrome c1 and cytochrome bh/l in the
oxidation of ubiquinol to ubiquinone. Are proton pumped across the
inner membrane?
ubiquinol transfers 1 e to c1 (thru R Fe-S) the semiquinone donates 1 e
to to BL to get (thru bH) to reduc 1 semiquinone to make ubiquinone.
Thus the b’s act as a recycling center for 1 e as the other goes on to IV
The energy for ATP synthesis is generated by the movement of protons from the ______________ side of the inner
mitochondrial membrane establishing a(an) _____________ gradient.
A) intermembrane; pH
B) intermembrane; electrical potential
C) matrix; sodium ion
D) matrix; pH
E) None of the above
The energy for ATP synthesis is generated by the movement of protons from the ______________ side of the inner
mitochondrial membrane establishing a(an) _____________ gradient.
A) intermembrane; pH
B) intermembrane; electrical potential
C) matrix; sodium ion
D) matrix; pH
E) None of the above
Ans: D
Section: 18.4
Provide a brief description of oxidative phosphorylation
It is the process in which ATP is formed, due to the transfer of electrons
from NADH or FADH2 to O2 by a series of electron carriers in the inner
membrane of the mitochondria
Explain why less ATP is made from the reoxidation of FADH2 as
compared to NADH
Complex II is not a proton pump. When electrons flow from FADH2 to
oxygen, as catalyzed by complex II, complex III, and complex IV, fewer
protons are pumped out of the matrix as compared to NADH. Thus,
fewer ATP molecules are ultimately made
In the malate-aspartate shuttle, how is oxaloacetate regenerated since
there is no transporter for oxaloacetate across the inner membrane?
Inside the mitochondria, the malate is converted to OAA by malate
dehydrogenase. The OAA is converted to aspartate, which can be
transported out of the mitochondria. The aspartate can then be
converted to oxaloacetate. The aspartate-oxaloacetate reactions
require glutamate and a-ketoglutarate.