Electron transport chain and oxidative phosphorylation - Part 1 Flashcards
After glycolysis and the CAC, how many net ATP were generated?
2 from glycolysis
2 from CAC (2 GTP)
Formation of 1,3-biphosphoglycerate in the GAPDH reaction and transfer of an inorganic phosphate to ADP to generate ATP is an example of what?
What is another example?
Subsrate-level phosphorylation
Formation of GTP duing succinyl-CoA synthetase reaction of the CAC
Up to the CAC, how many molecules of oxygen have been used thus far?
0
What were the oxidizing agents up to the ETC?
FAD and NAD+
How is the energy conserved in oxidative phosphorylation?
Conserved in the form of a proton gradient
In oxidative phosphorylation, ________ from NADH and FADH2 are transported to the ultimate electron acceptor, ________ via various protein-bound _______ centers present in the _______ mitochondrial membrane, and the energy of the _______ _______ is used to drive synthesis of ATP by the _________ system.
electrons oxygen (O2) redox inner proton gradient ATPase
What is the total practical amount of ATP generate by oxidative phosphorylation; by substrate level phosphorylation; in total, from one mole of glucose?
28
4
32
In most aerobic organisms, the ________ is the major site of the reactions of ____, ____ and ____ generation through ETC and oxidative phosphorylation.
mitochondria
PDC, CAC, ATP
The mitochondria is an independent structure with ____ membranes.
The ______ membrane is permeable to _____ and ______.
The ______ membrane is _______ inside and it is very strictly regulated. No ____ or _____ can cross unless aided by pumps or transport.
2 outer salts and water inner convoluted ions or water
What is the material between the inner and outer layers called?
Intermembrane space
Why is the inner membrane convoluted?
increase surface area
The matrix of the mitochondria contains all the enzymes required for ____, ____, ____ ____ _____, _____ _____ ____, ATP and ADP also present.
PDC
CAC
FA oxidation
AA oxidation
If the mitochondria leaks out, what occurs?
Pro-apoptotic proteins are released promoting cell death.
NADH and FADH2 have _____ reduction potentials.
low
The half reactions of NADH and FADH2 are ____.
The half reactions of oxygen is very ____.
The difference in reduction potentials is thus _____.
low
high
high (1.13V)
Why are the standard reduction potentials different in the different cytochromes?
All have iron but different electron densities in the proteins surrounding them, changing their ability to accept or lose electrons.
Virtually all the complexes of the ETC and OP are located where?
IMM
inner mitochondrial membrane
In complex 1, ______ is oxidized to ______ whereby _______ ___ accepts the electrons.
NADH
NAD+
coenzyme q10 (CoQ10)
How many protons get pumped out by the reaction in complex 1?
4
What is the enzyme for complex 2? Where else does it function?
Succinate DH
also used in the CAC
What is the reaction of complex 2?
Takes electrons from FADH2 and transfers them to Coq10.
No protons are pumped out but, the reaction is still exergonic
In complex 3, electrons from ______ are transferred to _________ _.
This results in ____ protons being pumped out.
coq10
cytochrome c
4
Complex 4 takes electrons ___ at a time from cytochrome c which are eventually transferred to oxygen to make _____.
Two electrons are needed to convert 1 oxygen _____ to ______.
This energy is sufficient to pump out ___ protons.
1 water atom water 2
When 1 NADH is oxidized, this leads to pumping of ____ protons.
10
How many protons can be pumped out by FADH2 oxidation?
6
Theoretically, how many ATP can be generated from NADH oxidation? FADH2 oxidation?
Practically?
3
2
2.5
1.5
Complex 1 catalyzes oxidation of _____ by _____ which then becomes _______ and ______ ____.
This is an ________ reaction.
NADH coq10 NAD+ reduced coq10 Exergonic
What is the problem with coq10 and cytc transfer of electrons?
Cytc can only accept 1 electron at a time so, coq10 reduces two cytc.
What is the problem with coq10 and cytc transfer of electrons?
Cytc can only accept 1 electron at a time so, coq10 reduces two cytc.
______ is the common electron acceptor for the reactions of complex 1 and 2
coq10
Cytc goes to _____ _ and gives electrons to _______.
____ cytc gives to ___ an oxygen atom.
complex 4
oxygen
2
1/2
Most of the electron carries (in ETC) except for ______ are proteins with _________ groups capable of accepting or donating electrons.
coq10
prosthetic
What are the three ways in which electrons are transferred in ETC?
Direct transfer: reduction of Fe3+ to Fe2+
Transfer of H atom
Transfer of hydride ion
- NADH oxidation to NAD+
What is another name for complex 1?
Mitochondrial NADH DH.
Other than coq10, what are other electron acceptors in complex 1?
FMN (flavin mononucleotide)
Fe-S (iron-sulfur centers)
What is another name for complex 2?
Succinate DH
How many cofactors does succinate DH have?
2
What is weird about complex 3 and coq10?
Coq10 is reduced and oxidized.
What is the name of complex 3?
Why?
Cytochrome oxidase
CytC doesn’t lose any hydrogens, just loses electrons, name is appropriate.
Ubiquinone is another word for ________ _.
it can accept one electron to become _______ or two to become ________
coenzyme q
semi-ubiquinone
ubiquinol
Why can coq10 move through the mitochondiral membrane?
Has a long hydrophobic chain (10x repeated) which allows it to be membrane soluble.
What part of coq10 participates in its reactions?
ubiquinone ring
What are flavoproteins?
Cofactosr which can take one electrons at a time, or 2 at once.
Iron-sulfur proteins are proteins containing an Fe-atoms ________ to sulfur atoms.
coordinated
Cytochromes are proteins with a ___-containing ____ prostehtic group.
Fe
heme
The heme group of cytc is _______ bound.
covalently
Cytochromes have a common heme group coordinated with _ _______ from surrounding rings.
4 nitrogens
What does B-hydroxybutarate generate?
NADH
In water, how is oxygen content determined?
Using a platinum oxygen electrode.
Detect current from transfer of electrons from the platinum electrode to oxygen to generate water.
What is rotanone?
Chemical that binds to complex 1 and blocks transfer of electrons.
What happens to oxygen consumption as rotanone is added?
No more oxygen consumption.
After addition of rotanone, how can oxygen consumption (or electron transfer) be resumed?
Add succinate
How does succinate resume oxidation after rotanone addition?
Complex 2 transfers electrons down the chain to resume oxygen consumption.
What happens to oxygen consumption if antimycin A is added?
Why?
Antimycin A blocks complex 3 and thus oxygen consumption
How can oxygen consumption be resumed after addition of antimycin A?
Add artificial substrate called TMPD along with vitamin C (ascorbic acid) which can directly transfer electrons to oxygen.
(This doesn’t happen in the body)
For the experiments with oxygen consumption and ETC, what is the first substrate added? Why?
B-hydroxybutrate
Will produce NADH by some of the mitochondrial enzymes
What do both cyanide and carbon monoxide block?
Complex 4
Suppose that complex 4 is blocked but everything else is fine, what occurs to complex 3? What happens to 1 and 2? CAC?
Complex will be functional but will not do anything.
Cytochrome c can get reduced but not oxidized so, it piles up causing a halt of complex 3.
Similarly, coq10 will then not get oxidized and backs up complexes 1 and 2.
Then, get accumulation of NADH and FADH2.
Accumulation of NADH then inhibits CAC, block PDC.
What is the better poison, rotanone or antimycin A?
What is an even deadlier poison?
Antimycin A since it blocks complex 3 and thus complexes 1 and 2.
Rotanone only blocks complex 1 so, complex 2 can still proceed and allow some ATP generation.
Carbon monoxide or Cyanide.
How can one live (not for too long) with rotanone exposure?
FADH2 can be generated from fatty acid oxidation
How many NADH from glycolysis?
How many ATP does that correspond to?
2
3-5
How many ATP generated in glycolysis?
CAC?
How many NADH from CAC?
FADH2?
How many ATP from ETC then (related to CAC)?
What is the total yield of ATP from one mol of glucose?
2 2 6 2 18
Total ATP = 32 4 ATP from substrate level phosphorylation \+ 2 NADH from PDC = 5 ATP 2 NADH from glycolysis = 5 ATP 6 NADH from CAC = 15 ATP 2 FADH2 from CAC = 3 ATP
