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102011 Oxidative Phosphorylation
UC MED 2015
34
Medical
Graduate
10/22/2011

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Term
How is energy yield calculated?
Definition
deltaGo = - (n)(F)(deltaEo)

n = number of electrons being transferred
F = Faraday constant (23 kcal/mol-volt)
DEo = Change in “Redox” potential under standard conditions (all reactants at 1.0 M concentration
Term
If an electron donor is a STRONGER donor than H2
Definition
the E will be negative
Term
For those compounds which will ACCEPT electrons from H2
Definition
the E will be positive
Term
Complex I contains:
Definition
6-7 Fe-S complexes and one FMN complex
Term
How many electrons can Complex I transfer at a time?
Definition
2
Term
For each pair of electrons entering Complex I, how many paris of protons are ejected into the intermembrane space?
Definition
2 pairs or 4 H+
Term
How many electrons can CoG carry?
Definition
1 or 2, when it carries 1 it is a radical
Term
CoQ is derived from?
Definition
Acetyl-CoA
Term
Complex IV (cytochrome oxidase) contains?
Definition
two copper containing electron carriers, and two iron containing carriers, cytochromes a1 and a3. The copper alternates between the Cu+1 and Cu+2 states as the electrons are passed along the chain
Term
Once 4 electrons are within Complex IV , what can happen?
Definition
O2 can be reduced to H2O
Term
Complex II contains?
Definition
succinate dehydrogenase
Term
Complex II is the entry site of what from the TCA cycle?
Definition
FADH2
Term
The force is generated across the inner mitochondrial membrane, and consists of two components and this force is called?
Definition
It is called the Proton Motive Force (PMF)

It is based upon pH and concentration of protons
Term
What can block ATP synthesis by blocking the proton channel in ATP synthase?
Definition
Oligomyocin
Term
What are the Principles of the Chemiosmotic Hypothesis?
Definition
1) The electron transfer chain must be asymmetrically oriented across the membrane such that protons are ejected
2) Mitochondria must be capable of ejecting protons in the presence of substrate and oxygen
3) Permeabilizing membranes to protons should disrupt oxidation and phosphorylation
4) The mitochondria must contain a proton driven ATP synthase
Term
Inner mitochondrial membrane ___________ to NADH
Definition
impermeable (note there is no carrier for NADH either)
Term
What NADH shuttle in the cytosol transfers electrons to FAD in mitochondria – 1.5 ATP per cytosolic NADH (skeletal muscle, brain)?
Definition
Glycerol-3-Phosphate Shuttle
Term
What shuttle does this...NADH in the cytosol eventually transfers electrons to NAD+ in the matrix – 2.5 ATP per cytosolic NADH (liver)?
Definition
Malate-aspartate shuttle
Term
What dissipates the proton gradient by allowing membrane to become permeable to protons? ATP synthesis cannot function, but respiration continues at a greater rate to attempt to re-establish the proton gradient.
Definition
Uncouplers
Term
What is a natural uncoupler found in brown fat, which is activated by norepinephrine? Activation of this protein (also known as UCP1, uncoupling protein 1) allows dissipation of the proton gradient to allow heat to be generated. Predominant in newborns.
Definition
Thermogenin
Term
How can one inhibit oxidative phosphorylation?
Definition
1) Block electron flow along the chain
2) Block the activity of ATP Synthase
3) Allow free ion flow across the inner mitochondrial membrane
Term
What can block Complex IV in the ETC?
Definition
CN, CO
Term
What can block Complex III in the ETC?
Definition
Antimycin A
Term
What can block Complex I in ETC?
Definition
Rotenone and Amytal
Term
What can block ATP synthase?
Definition
Oligomycin and DCCD (both block proton entry)
Term
What are the uncouplers that are permeable to protons?
Definition
CCCP, DNP, and Thermogenin
Term
What are the uncouplers that are permeable to potassium ions?
Definition
Valinomycin
Term
What block ADP entry into the mitochondria thus ATP/ADP exchange can't occur?
Definition
Atractyloside
Term
How does phosphate enters the mitochondria?
Definition
With protons via a symport known as the Phosphate Translocase
Term
How does ADP enter the matrix?
Definition
Via Adenosine Nucleotide Translocase- it is an antiporter that brings in 3 ADP and takes out 4 ATP
Term
How is oxidative phosphorylation regulated?
Definition
It is regulated by energy charge-values range from 0 to 1.
Term
What is the normal energy value?
Definition
0.8
Term
If the energy charge is less than 0.8?
Definition
energy production is stimulated
Term
If the energy charge is >0.8?
Definition
ADP supplies in the mitochondria become rate limiting for ATP production, and production ceases
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