26 - OxPhos Regulation Flashcards
A successful OxPhos must accomplish what key goals?
1) Transfer electrons from NADH and FADH2 — O2
2) Establish a proton gradient across the inner mitochondrial membrane
3) To synthesize ATP
Electrons flow from the molecules with (LOWER/HIGHER) Eo (standard redox potential – energy) to that with the (LOWEST/HIGHEST) Eo. The difference in Delta Eo is associated with Delta G, which are inversely related.
Lower
Highest
Electron transfer through the respiratory chain lead to the pumping of _____ from matrix to the inner-mitochondrial space.
H+
Two factors constitutes a proton-motive force (pmf) to drive ATP synthesis by complex V. These factors are…
1) pH gradient
2) Membrane potential
Who proposed the chemiosmotic hypothesis (1961/1978), making it a revolutionary idea at the time?
Peter Mitchell
The chemiosmotic theory consist of 3 postulates. Postulate 1 – The mitochondrial electron-transport chain translocates ________ across the inner mitochondrial membrane as electron flows from one respiratory electron-transport chain complex to the next.
Protons
The chemiosmotic theory consist of 3 postulates. Postulate 2 – ATP synthase uses the proton motive force (pmf) to drive the phosphorylation of ______.
ADP
The chemiosmotic theory consist of 3 postulates. Postulate 3 – The inner mitochondrial membrane is _________ to H+ and OH- ions. If the membrane is disrupted, a pmf cannot be established, and ATP synthesis does not occur.
Impermeable
ATP synthase is called complex _____ and is embedded in the inner membrane of the _________.
V
Mitochondria
ATP synthase has a ball and stick structure. The _____ subunit is the stick and is embedded in the membrane and has a proton channel. The _____ subunit is the ball, and protrudes into the matrix side, it contains catalytic domains.
F0
F1
The F1 subunit of ATP synthase is composed of what?
alpha-3 beta-3 gamma delta epsilon
In the F1 subunit of ATP synthase, how are the alpha and beta subunits arranged?
Alternately in a hexameric ring
In the F1 subunit, both alpha and beta subunits can bind nucleotides but only _______ are catalytically active.
beta
In the F1 subunit, above the alpha and beta is a stalk made of what proteins?
gamma
epsilon
In the F1 subunit, the _______ subunit has a long helical coil that extends into the center of the alpha-3 and beta-3 hexamer.
gamma
ATP synthase molecules associate with each other to form ________, which come together to form ________.
Dimers
Oligomers
ATP synthase oligomers stabilize the individual molecules to ________ forces required for catalysis, and maintains curvature in the inner membrane.
Rotational
________ allow the proton gradient to be in close proximity to the ATP synthase.
Cristae
This is an inhibitor that disrupts proton transport through the channel in ATP synthase.
Oligomycin
Making and exporting one ATP costs about _____ hydrogens (protons).
4
ATP and ADP are not permeable across the mitochondrial membrane, they need a carrier which is called…
ATP-ADP translocase
ATP-ADP translocase reside in the outer and inner mitochondrial membranes and works with mitochondrial carriers. It was recently assigned as complex _____.
VI
The flow of ATP and ADP is ________, this means ADP enters the matrix only if ATP leaves the matrix.
Coupled
Reduced NADH cannot cross the mitochondrial membrane, so two shuttle systems are used which are…
1) Malate-aspartate shuttle
2) Glycerophosphate shuttle
This shuttle operates in the heart, liver, and kidneys. It generates reduced NADH in the mito-matrix. From this, reduced NADH enters to the ETC at Complex-I.
Malate-aspartate shuttle
This shuttle operates in the skeletal muscle and brain. It generates reduced FADH2 in the inner mito-membrane. Reduced FADH2 joins to ETC at CoQ.
Glycerophosphate shuttle
Levels of _____ regulate respiration. Electrons flow through ETC only when _____ is phosphorylated to _____.
ATP
ADP
ATP
Regulation by ADP levels called ________ control or _______ control.
Respiratory
Acceptor
When the transfer of electrons is inhibited in OxPhos, what happens?
1) Decrease in the pumping protons
2) Decrease in the protein gradient
3) Inhibition of ATP synthesis
Some organisms can uncouple OxPhos from ATP synthesis. Instead, it is used to generate ______ and maintain ______ ______ (hibernating animals).
Heat
Body temperature
Uncoupling of OxPhos happens in this tissue, which is rich in mitochondria and get its color due to cytochrome and hemoglobin.
Brown adipose tissue
The inner mitochondrial membrane contains uncoupling protein _____, also called ________.
UCP 1
Thermogenin
UCP 1 transfers protons from the cytoplasm to the matrix side and energy is converted to _______ instead of ATP.
Heat
UCP 2 and UCP 3 also uncouple OxPhos from ATP synthesis. They play a role in…
Energy homeostasis
UCP (proton leak) in the production of heat is important for the thermogenesis in what tissue?
Brown adipose tissue
