Studied by 66 PeopleTags & Description
lipid, carbohydrate, and protein metabolism
AcetylCoA is the end product of ____.
nucleotides—NADH and FADH2.
AcetylCoA is used in the TCA cycle to generate reduced ____ .
proton gradient across the inner mitochondrial membrane.
reduced nucleotides then donate their high energy electron into the electron transport pathways, which generates a _____
ADP and Pi
That proton gradient is used by ATP synthase to drive the synthesis of ATP from ____
inner membrane of the mitochondria
In eukaryotic cells, the electron transport and oxidative phosphorylation systems are located in the ____ of the ______
--electron transport driven proton pumping and proton driven ATP synthesis.(These two processes work in tandem to produce ATP from reduced nucleotides such as NADH and FADH2. )
Oxidative phosphorylation is a composite of two biochemical processes____ and ____
electron transport
_____ is a process in which the transport of protons out of the mitochondrial matrix is energized by the flow of electrons through various protein complexes within the mitochondrial inner membrane and leads to the formation of a proton gradient with high proton concentration in the intermembrane space and low proton concentration in the mitochondrial matrix.
ATP synthase, downhill
The _____ enzyme uses the proton gradient formed by electron transport to drive the synthesis of ATP. Protons flow downhill from the intermembrane space through the ATP synthase protein. The ___ flow of protons (from an area of high concentration in the intermembrane space to an area of low concentration in the mitochondrial matrix) through the ATP synthase energizes the synthesis of ATP from ADP and inorganic phosphate.
electron transport
In the _____ phase, reduced nucleotides pass their electrons through a series of enzyme bound cofactors. At various stages of the electron transport system, the downhill transfer of electrons is coupled to the uphill transport of hydrogen ions. The hydrogen ions are pumped from the inner matrix of the mitochondria to the region between the inner and outer mitochondrial membranes.
phosphorylation
_____ phase, the hydrogen ion gradient, created by the oxidative proton pumps, is used to drive the synthesis of ATP from ADP and Pi. In this process, the protons flow through an ATPase down their concentration gradient back across the inner mitochondrial membrane.
respiratory
The ____ chain consists of four complexes: Three proton pumps and a physical link to the citric acid cycle.
complex 1
High potential electrons from NADH enter the system at NADH-Q oxidoreductase
complex 1
-Electrons flow from NADH to coenzyme Q through _____. The flow of electrons through is coupled to the pumping of four protons out of the matrix of the mitochondrion into the space between the inner and outer mitochondrial membrane.
complex 2
-Electrons from FADH2 (which have a lower potential than those from NADH) flow to coenzyme Q through _____. This complex does not pump any protons.
1 or 2
-Two electrons are carried through the mitochondrial membrane from complex __ or complex ___ to Q-cytochrome c oxidoreductase by reduced coenzyme Q (QH2). This coenzyme is lipid soluble and always stays in the membrane.
complex 3
Two electrons flow from QH2 through Q-cytochrome c oxidoreductase to the water soluble protein cytochrome c. The flow of electrons through] is coupled to the net transport of four protons into the space between the inner and outer mitochondrial membrane and the uptake of two protons from the mitochondrial matrix. Each molecule of reduced cytochrome c carries one electron from Q-cytochrome c oxidoreductase to cytochrome c oxidase
NADH , FADH2 , FMN , Non-heme iron sulfur complexes, Ubiquinone, Cytochromes b, c1, c, a, a3
cofactors that participate in electron transport.
absorption spectra
alterations in the____ occur in various cofactors depending on their oxidation states. These changes are useful in following the progress of a biochemical reaction.
FMN
The first acceptor of electrons from NADH in complex I is ___
FMN, FMNH2
The reduction of ___ to ___ occurs on the same isoalloxizine ring and has essentially the same chemistry as we have previously seen with the conversion of FAD to FADH2.
FMN, FMNH2, double
When the ____ cofactor is reduced to ____, it accepts two electrons and two protons on the isoalloxizine ring. The protons occupy sites where there were paired electrons on two of the ring nitrogen atoms. There is a shift in the ____ bond pattern on two of the isoalloxizine rings when the additional electrons are added to the system.
3
There are ____ types of iron-sulfur clusters involved in the electron transport scheme
4, 2
The proximity of the ____ protein sulfur atoms aids in the oxidation-reduction reaction and helps determine the energy levels of the ____ oxidation states.
accept
The lipid soluble cofactor ubiquinone (aka coenzyme Q) can ___ two electrons and two protons.
semiquinone, ubiquinol.
The addition of one electron and one proton produces a ____ (a free radical with an unpaired electron). It is a very reactive and unstable intermediate that has to be closely sequestered within the active sites of enzymes. The addition of a second electron and proton produces the stable, reduced intermediate ___
coenzyme Q
The ____ molecule carries electrons within the inner mitochondrial membrane between complex I and complex III. It also functions to carry electrons between complex II and complex III, and also within the cytochrome c reductase complex
cytochrome, covalently,
The ____ proteins all contain heme prosthetic groups with a tetrapyrrole organic structure and a central iron ion. They are ___ attached to the cytochrome protein molecules by thioether bonds to protein cysteine residues. The cytochromes differ from one another in protein sequence, the structure of the attached heme group, the absorption spectrum, reduction potential, and their role in the electron transport scheme.
cytochrome c
____ has an absorption spectrum. It absorbs light in the visible wavelength, giving it a color that is visible to the human eye. That spectrum changes depending on whether the molecule is oxidized or reduced. Such changes in absorption are useful to biochemists, because they provide a window through which investigators can follow the reaction progress as these molecules are oxidized and reduced
cytochrome c
____ molecule is a comparatively small protein with only 104 amino acids and easy to purify
1, 3, 3
when NADH is the donor, the electrons flow from complex ___(NADH coenzyme Q reductase) to complex ____(coenzyme Q cytochrome c reductase) and then to complex ___ (cytochrome c oxidase).
complex 1 (NADH coenzyme. Q Reductase)
two electrons flow from NADH to coenzyme Q. The pathway of electron flow is NADH to FMN, through a series of iron sulfur proteins, to coenzyme Q. The final product of this process is reduced coenzyme Q (QH2). The flow of electrons through is coupled to the pumping of four protons out of the matrix of the mitochondrion into the space between the inner and outer mitochondrial membrane. Two additional protons are taken up from the matrix to convert coenzyme Q to QH2.
complex 2 (cytochrome c reductase)
cytochrome c reductase. The QH2 that is produced in complex I diffuses through the hydrophobic membrane to complex III. There is an interesting transition in this complex. That is, QH2 feeds two electrons into the complex, but cytochrome c only accepts one electron. As a result, it takes two cycles of reduction involving two cytochrome c molecules to effectively convert coenzyme Q from the reduced to oxidized form
donates, radical
In the first cycle (part A), the reduced coenzyme Q ___ two electrons. One electron goes through an iron-sulfur protein and a protein bound cytochrome c1 to cytochrome c. The other electron goes to a protein bound coenzyme Q molecule to form a free ____, then through two variants of cytochrome b, and finally ends up in a second coenzyme Q as a free radical with an unpaired electron.
closely
free radical intermediate is extremely reactive and could damage the cell if it were set free from the surface of the enzyme. Fortunately, the enzyme complex holds the intermediate ____ until further reaction can occur.
donates, converting
second molecule of reduced coenzyme Q ___ two electrons. One electron follows the same pathway as in the first cycle-- through an iron-sulfur protein and a protein bound cytochrome c1 to cytochrome c. The second electron follows the pathway used by the second electron in the first cycle and ends up ___ the free radical back to reduced coenzyme Q.
2, 4,
result of this is ___ molecules of reduced coenzyme Q donate ____ electrons. Two of those electrons produce two molecules of reduced cytochrome c, and the other two electrons end up regenerating a molecule of QH2.
reduction
The end result of this series of reactions is the _____ of molecular oxygen (O2) to two molecules of water. It takes two electrons to reduce each oxygen atom to water, so four electrons are required
4, reduce, matrix
During the process of converting molecular oxygen to water, __ electrons from reduced cytochrome c and four protons from the matrix are used to ___ the two oxygen atoms to water. In addition to the four “chemical protons” absorbed from the matrix and incorporated into water, four additional protons are pumped from the ___ to the intermembrane space.
gradual, pump
as the electrons pass through the various carriers, there is a ___ loss of reducing potential and a corresponding release of energy. Some of that energy is used to ____ protons across the inner mitochondrial membrane to create a proton gradient.
Nernst Equation
tells us that the reduction potential for any reaction is equal to the standard state reduction potential plus RT/nFln (electron acceptor)/(electron donor).
equation for an oxidation-reduction reaction
standard state voltage change (ΔE0’) for the combined reaction equals the standard reduction potential for the electron acceptor (the substance being reduced) minus the standard reduction potential for the electron donor (the substance being oxidized).
standard state free energy change for a reaction
ΔG0’ = -nFΔE0
electron transport
constant drop in reduction potential (voltage)—meaning there is a continuous loss of energy.
proton gradient
The connection between electron transport and oxidative phosphorylation is through the ____
2, 5
The F0 component consists of ____ different protein subunits, and the F1 component contains ____ different subunits.
F1,
When the __ component of the ATP synthase is removed, the ability to synthesize ATP is lost. When the F1 component is added back, the reconstituted preparation regains the ability to synthesize ATP.
F1
The ____ complex has 3 α and 3 β subunits surrounding a central γ subunit. forms are interconvertible. The α subunits bind ATP but do not participate in any catalytic or transport reaction.
proton
___ driven ATP synthesis involves a binding change mechanism, in which three sequential 120o rotations of the γ subunit drive the β subunits through three different forms, T (tight), O (open) and L (loose).
T
The subunit in the ___ form converts ADP and Pi to ATP, but does not allow the ATP product to be released
T, O
When the γ subunit is rotated by 120 degrees in a counter clockwise direction, the ____ form is converted into the ____ form, allowing ATP release. Then ADP and Pi can bind to the O form. An additional 120 degree rotation traps ADP and Pi in the L form.
F0, a, c
The membrane spanning ____ component consists of __ and ___ subunits. The c subunit consists of two α-helix structures with a negatively charged aspartate in the center. The a subunit contains a cytoplasmic and a matrix half-channel.
c, 2, center
Each of the ____ subunits consists of ___ α helices. Between 10 and 14 of the c subunits form a membrane spanning ring. An aspartic acid residue in one of the helices lies at the ___ of the membrane. These aspartate residues are protonated and deprotonated during the passage of protons around the ring.
proton
____ movement across the membrane drives rotation of the c ring. With this charge neutralized, the c ring can rotate clockwise by one c subunit. This moves another protonated aspartic acid residue out of the membrane and into contact with the matrix half-channel. This proton can diffuse into the matrix, resetting the system to its initial state.
glycerol 3-phosphate shuttle
translocation of NADH from the cytoplasm to the mitochondria.
malate-aspartate shuttle
In heart and liver, electrons are carried into the matrix by the ____
2.5 and 1.5,
____ ATP's were generated from NADH, whereas ____ ATP's could be derived from FADH2
electrons
____ from NADH pass through complex I, which pumps protons, and then go on through complexes III and IV, which also pump protons
FADH2
Electrons from ___ pass through complex II, which does not pumps protons, and then go on through complexes III and IV, which do pump protons
less
As a result, there is ____ of a proton gradient produced from FADH2, and thus less ATP is produced
30
ATP production, the complete oxidation of one glucose molecule should yield about ____ ATP’s.