L8 Oxidative phosphorylation Flashcards
What is the function of NADH dehydrogenase (Complex I)?
Transferring electrons from NADH to unbound ubiquinone (Q) to form ubiquinol (QH2)
Each Fe is always coordinated by how many S in the Iron-sulfur clusters?
4
What is the function of succinate dehydrogenase (Complex II)?
Transferring succinate to fumarate
Is there any proton pumping in Succinate dehydrogenase (Complex II) ?
No
Which complex is the only membrane -bound enzyme in TCA cycle?
Complex 2: Succinate dehydrogenase
What is the function of Cytochrome oxidase (Complex IV)?
Transfers electrons from cytochrome c to oxygen
For every 2 electrons donated by NADH, how many ATPs are synthesized?
2.5
For every 2 electrons donated by FADH2, how many ATPs are synthesized?
1.5
How many electrons NAD+/NADH and NADP+/NADPH carries at a time?
2
Is NAD+/NADH and NADP+/NADPH diffusible or bound in enzymes?
Diffusible
Is FAD/FADH2 and FMN/FMNH2 diffusible or bound in enzymes?
Bound in enzymes
What is the highly folded inner membrane called?
Cristae
Where does the electron flow occur?
The inner membran of mitocondria
The energy released form the electron transference is used for what process in NADH dehydrogenase (complex I) ?
Proton pumping from the matrix ito intermembrane space
What is the initial electron donor of the oxidative phosphorylation?
NADH
How many electron and proton can FMN transfer at a time?
1
What is the final eletron carrier in complex one?
Q/QH2
Are they any energy release in Complex II?
Yes, but really little (-2kJ /mol), not enough to pump the proton
What are the electron carriers in Complex III?
Complex III is called cytochrome bc1 complex
(1) Fe-S clusters
(2) Cytochrome b
(3) Cytochrome c1
Is cytochrom c water soluble?
Yes
What is the main result of the first round in the Q cycle?
QH2 becomes a half-reduced semiquinon (.Q-)
WHat are the electron carriers in cytochrome oxidase(complex IV)?
2 Cu ions and 2 heme A groups (cytochrome a proteins)
In which complex in the ETC:
O2 is used up and water is generated?
Complex IV
Cytochrome oxidase
Oxygen oxidized which molecule in cytochrome oxidase (complex IV)?
cytochrome c
How many proton does Complex four pumped out?
2 protons per 2 electrons
The energy stored in the gradient, proton-motive force, has two components, what are they?
(1) Chemical potential energy (inside the membrane: alkaline)
(2) Electrical potential energy (inside the membrane: negative)
What are the two units of ATP synthase?
F0 and F1
Protons flow through which unit of ATP synthase?
F0
ATP is synthesized by which unit?
F1
Why NADH need to have a shuttle system?
Because inner mitochondrial membrane is impermeable to NADH
What are the two different shuttle system for NADH?
(1) Glycerol 3-P shuttle system
(2) Malate-aspartate shuttle system
What does reducing equivalents mean?
Molecules that can be transported into the mitochondria
In Glycerol 3-P shuttle system, which electron carrier acts as the reducing equivalents?
FAD/ FADH2
In Glycerol 3-P shuttle system, which two complex are skipped?
Comlex one and Complex two
Glycerol 3-P shuttle system takes place in which kind of human tissues?
Skeletal muscle and brain
Malate-aspartate shuttle system takes place in which kind of human tissues?
Liver, kidney, and heart
What is the key enzyme involved in the glycerol 3-P shuttle system?
G-3P dehydrogenase
What are the key enzymes involved in the Malate-aspartate shuttle system?
Dicarboxylate translocase adn Glutamate-aspartate translocase
What is the main difference between Glycerol 3-P shuttle system and Malate-aspartate shuttle system regarding the involvement of the complex in ETC?
Glycerol 3-P shuttle system involes only III and IV, while Malate-aspartate shuttle system involves I, III and IV
