Chapter 18: Electron Transport Chain and Oxidative Phosphorylation Flashcards
Free energy via a proton gradient drives the synthesis of ATP from ADP and Pi via:
a) Oxidative phosphorylation
b) Substrate level phosphorylation
a.
T/F the inner mitochondria membrane separating the matrix from the intermembrane space is impermeable to almost everything, including protons and OH.
True.
T/F outermembrane of the mitochondria is permeable to many things, excluding items such as acetyl coA, oxaloacetate or NADH and large proteins
True.
the ETC ____ NADH and FADH2 to ____ O2 into H2O. The redox energy is used to ____ out of the ____ and into the ____, forming an electrochemical gradient.
the ETC OXIDIZES NADH and FADH2 to REDUCE O2 into H2O. The redox energy is used to PUMP PROTONS out of the MATRIX and into the INTERMEMBRANE SPACE, forming an electrochemical gradient.
What’re the 2 main shuttle systems of NADH?
1) the malate aspartate shuttle
2) the glycerophosphate shuttle.
the malate-aspartate shuttle pushes ____ from the inner membrane space, past the impermeable inner mitochondrial membrane into the _____
the malate-aspartate shuttle pushes NADH (in the form of malate) from the inner membrane space, past the impermeable inner mitochondrial membrane into the MATRIX
Draw the Malate Aspartate shuttle
refer to notes
What’re the 2 transporters of the Malate Aspartate shuttle
malate-alphaketoglutarate transporter, and the glutamate-aspartate transporter
in the malate-aspartate shuttle, malate crosses from the ____ to the ___ of the mitochondria, and aspartate is created in the ____ and is transported to the _____.
in the malate-aspartate shuttle, malate crosses from the INNER MEMBRANE to the MATRIX of the mitochondria, and aspartate is created in the MATRIXand is transported to the INNER MEMBRANE.
T/F: Cells that use the glycerophosphate Shuttle as a method of transporting NADH across the inner membrane of the mitochondria get one less ATP per glucose than cells using the malate-aspartate shuttle. Why or Why not?
True. Because the glycerophosphate shuttle creates FADH2 in the matrix, instead of NADH. FADH2 is less energetic than NADH, in the sense that FADH2 is worth 1.5 ATP, and NADH is worth 2.5 ATP, THUS 1 ATP LESS.
Draw the glycerophosphate shuttle system
refer to notes
the more positive the reduction potential, the _____ the liklihood of the compound having a higher affinity for electrons.
the more positive the reduction potential, the higher the likelihood of the compound having a higher affinity for electrons.
the more positive the potential, the greater the species’ affinity for electrons and tendency to be reduced.
FAD+ had a redox potential of -0.219V, and NAD+ has a redox potential of -0.315 V(more negative). Is NADH of FADH2 a stronger reducing agent? Why?
the standard reduction potential for FAD is less negative than for NAD+ (-0.219 vs. -0.315 V). This means that NADH has a more positive oxidation potential (+0.315) and hence is a better reducing agent (will donate more electrons) than FADH2, thus yields more energy when it coughs up its electrons, resulting in greater ATP production.
A solution with a higher (more positive) reduction potential than the new species will have a tendency to _____ electrons from the new species (i.e. to be reduced by oxidizing the new species) and a solution with a lower (more negative) reduction potential will have a tendency to ____ electrons to the new species (i.e. to be oxidized by reducing the new species).
A solution with a higher (more positive) reduction potential than the new species will have a tendency to GAIN electrons from the new species (i.e. to be reduced by oxidizing the new species) and a solution with a lower (more negative) reduction potential will have a tendency to LOSE electrons to the new species (i.e. to be oxidized by reducing the new species).
What is the adenine nucleotide translocase antiporter (ANT). How is it facilitated? What 3 transporters are involved?
a shuttle in the inner mitochondrial membrane that transports ATP OUT OF THE MATRIX, while bringing ADP INTO THE MATRIX. It’s run by using the mitochondrial electrochemical gradient.
1) adenine nucleotide translocase antiporter
2) ATP synthase
3) phosphate translocase symporter
Draw the Adenine Nucleotide Translocase Antiporter system
refer to notes
T/F the protein complexes in the electron transport chains have higher and higher affinities for e-.
True.
Recall; FADH2 does not release its electrons as well as NADH and has a lower energy level. This means that the it needs to drop off its electrons at further points of the ETC where the proteins have such high electron affinities (want to be reduced) that the FADH2 can give its electrons (oxidize).
electrons from NADH are carried from complex 1 to complex 3 by ____
coenzyme Q
electrons are carried from Complex 3 to complex 4 by ____
cytochrome c
Ubiquinone can carry ____ electrons, where as cytochrome c carries ___ electrons
Ubiquinone can carry 2 electrons, where as cytochrome c carries 1 electron.
Complex 2 accepts electrons from ____, as is getting converted into _____
Complex 2 accepts electrons from succinate, as it gets converted into fumarate.
Where is ubiquinone located?
in the intermembrane bilayer
Where is cytochrome c located
in the intermembrane space.
complex 1 pumps out ___ protons into the inner membrane space
pumps 4 protons
T/F: CoQ acts as a “collection point for all electrons” and collects electrons from both NADH or succinate
True. collects electrons from both protein 1 and protein 2
in terms of proton pumping, why is FADH2 worth less electrons than NADH?
no proton pumping occurs in complex 2 and there is less of a contribution to redox energy (less of a difference in redox potentials). This makes FADH2 worth less ATP.
The electron transport chain is made of carrier molecules assembled into 3 protein complexes, and the passage of an electron through each complex generates enough energy to make roughly 1 ATP per complex. NADH enters the cycle at the first complex, so NADH produces 3 ATP. FADH2 enters the cycle at the 2nd complex, thus generating 2 ATP. (because less protons are pumped across since it bypasses the first complex)
(recall; roughly 3 atps needed to make 1 atp).
how many oxidations of cytochrome c is needed in order to reduce O2 into H2O
4 cycles of cytochrome c oxidations, because cytochrome c carries 1 electron at a time.
under standard conditions, what is the expected concentrations of all products and reactants?
1 molar, therefore, Q =1
Which is the irreversible step of the electron transport chain?
when complex 4 uses the electrons donated by cytochrome C in order to reduce oxygen into O2.
Define the chemiosmotic theory
when free energy from electron transport is conserved by pumping hydrogen from the mitchondrial matrix to the intermembrane space to create an electrochemical proton gradient across the inner mitochondrial membrane. The electrochemical potential of this gradient is harnessed to synthesize ATP.
How does brown adipose tissue create heat?
has a transporter to allow H+ back into the mitochondria without coupling it to ATP synthesis.
Energy held in the proton concentration gradient made by the NADH, FADH2 etc. becomes heat instead and is used to warm the organism.
What step in complex 1 provides the most energy?
the second step, when Q gets reduced to QH2, which pumps 4 protons out of the matrix, resulting in energy being created via a proton concentration gradient.
in the glycerophosphate system, NADH gets ___ in the cytosol by DHAP.
NADH gets oxidized by DHAP, which turns into glycerol 3 phosphate. the electrons are then given to FAD+ in the mito membrane, turning into FADH2.
draw the krebs cycle
refer to notes
Which of the following compounds can not cross the inner mitochondrial membrane (without first being converted into something else)?
a. pyruvate
b. malate
c. citrate
d. oxaloacetate
e. aspartate
d) oxaloacetate. the others can cross the membrane because there are transporters for them.
