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43 Cards in this Set

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In the ETC, where do complexes I and II receive their electrons from?
.
Complex I: NADH

Complex II: FADH2

.
a. Where does complex III receive its electrons from? b. what intermediate delivers the electrons?
.
.
.
a. Complexes I and II

b. Coenzyme-Q

.
What does complex III do with its electrons?
Gives them to Cytochrome-C
What does cytochrome-C do with its electrons?
Gives them to complex IV.
Where is oxygen reduced to water?
complex IV
What happens at complex V?
It is ATP synthase.
What delivers electrons to Complex II?
Succinate --> fummarate (using succinate dehydrogenase which is stuck to the complex)... (FADH2 is the product of this reaction)
How is cytochrome-c different from other components of the ETC?
its water soluble.
What is the word for a metal ion or organic molecules (coenzyme) that assists proteins in the catalytic activity?
.
Cofactor
What is the name of the subclass of cofactors which bind tightly?
.
Prosthetic groups
Does a cofactor with a postive reduction potential make a strong acceptor or donor of electrons?
Acceptor
Does a cofactor with a negative reduction potential make a strong acceptor or donor of electrons?
Donor
NAD attaches loosely to proteins, would it be a prosthetic group?
.
No, but it would still be a cofactor.
What are porphyrins?
organic molecules that typically have a metal ion in the, which can act as an electron acceptor.
.
what are the charges of ferric and ferrous?

Note:
cyto. b5 (Fe+3) complex overall charge= +1

cyto. b2 (Fe+2) complex overall charge =neutral

Thus, how can a protein environment have an effect on reduction potential?
?
Why would a charged molecule, such as a prophyrin (+), be more likely to accept an electron in a hydrophic environment?
.
Because if it accepts an electron it becomes neutral and be "happier" in a hydrophobic environment... opposite logic would be true too.
.
What does a heme/porphyrin do if placed in an amino acid that is very polar and positively charged? Why?
.
heme/porphyrin is neutralized... because polar (+) charged the heme/porphyrin will accept an electron and be neutralized.
What does a heme/porphyrin do if placed in a hydrophobic amino acid?
.
heme/porphyrin will want to donate electrons.
.
Hemes in cytochrome have a reduction potential of .22V, is it a good acceptor donor?

Which would be a better donor... a more negative or a more positive molecule?

Which is a better donor of electrons, NADH or FADH2?
.
acceptor

More negative

NADH
a. Some proteins are very polar, what will happen to the heme group?

b. some proteins are nonpolar, what effect does this have on hemes with a good reduction potential?
a. it will neutralize the heme

b. it forces them to be reduced.
a.How are non carbonoid (carbons w/ a single metal ion called Fe-S complexes), attached to the protein?

b. what happens to the Fe?
a.Cysteine residues on the Fe-S complexes
b. redox... Fe (III) to Fe (II)
At the end of the ETC, what redox activity is responsible for oxidizing O2 to H2O?
Cu (II) to Cu (I)
The thermodynamic gradient that we go down (1.14 V) in the ETC, as NADH and FADH2 transfers it electrons, is equivalent to how many kcal/mol?
it is equivalent to 52.6 kcals/ mole
What oxidizes NADH and reduces coenzyme-Q?
Complex I
a. What does NADH dehydrogenase mean?

b. Likewise, what does NADH coenzyme q reductase (an enzyme) mean?

c. are both a and b?
a. It means NADH is being oxidized.

b. an enzyme which removes electrons from NADH and delivers them to coenzyme q so that NADH is oxidized and coenzyme q is reduced.

c. both are different names for complex I.
What exactly is happening in complex I?
--> NADH transfers its electrons to FMN
--> reducing it to FMNH2
--> delivering them to the Fe-S cluster
--> and ultimate to coenzyme Q
a. what is the overall gradient that those electrons flow down from complex I to coenzyme Q?

b. How is this energy captured?

c. what is the kcal equivalent?
a. 330mv

b. proton gradient (4 protons are pumped into the inner membrane space)

c. 15 kcal/mol
Complex II is known as succinate coenzyme Q reductase. What does this mean?

b. what is another name for this enzyme? (complex II)

c. where is this also found?
This is simply telling you that succinate is transferring its electrons (that is, it is being oxidized) to coenzyme Q

b. succinate dehydrogenase

c. TCA cycle
a. what is the overall gradient that those electrons flow down from complex II to coenzyme Q?

b. What is the kcal/mol equivalent?

c. what effect does the energy flow have on tbe proton gradient

d. what ramifications does this have for FADH2?
a. 29mV

b. 1.3 kcal/mol

c. the mV is so low, there are are no protons pumped out of the matrix.

d. FADH2 doesn't cause the export of H+ until complex III
a. What is complex III known as?

b. What does it do?
a. Coenzyme Q cytochrome C reductase

b. it is the enzyme that transfers electrons one-at-a-time from Co Q to Cyt C.
a. What is cytochrome C?

b. what is the gradient produced by cyt c?

c. What is the kcal/mol equivalent?
a. A series of reduction steps, electron transfers, which is used to pump protons out of the matrix.

b. 310mV

c. 14 kcal/mol
a. As 2 protons (which are equal to the number of electrons) are pumped out by cyt C, how many protons end up in the intermembrane space?

b. how is this possible?

c. what is a special attribute of cyt C?
a. 4

b. two of the protons come from the oxidation of coenzyme Q

c. water soluble
a. cytochrome C is 220mV... is it a good acceptor? Why?

b. Where do the electrons from cyt C end up?
a. yes, because the Fe-S clusters are sandwich between the hydrophobic amino acids... going from positive to neutral.

b. complex IV
a. What is complex IV also know as?

b. What is happening in the complex besides oxidation?

c. What is the electrochemical gradient is worth for 2 electrons in?

c. For every two electrons that flow through, how many protons are transferred out of the matrix.

e. how many electrons must flow through the ETC to completely reduce oxygen to water?
a. cyt C oxidase (because it is oxidizing cyt C)

b. O2 is be reduced to water.

c. 14.8 kcals/mol

d. Two

e. four
a. What can oxidize superoxide, which can protect DNA from mutation?

b. what is a consequence of SOD?

c. how many forms of SOD are there?
a. Superoxide dismutase (SOD)

b. SOD can be oxidized to form peroxide, but this can be deactivated too.

c. mitochondrial and cytoplasmic
a. What does Rotenone do?

b. why does Rotenone knock out the ETC, when you can still deliver electrons through Complex II?

d. what does Amobarbitol do?
a. It is a known inhibitor of complex I. It binds to complex I and it prevents electrons from flowing all the way from NADH to coenzyme q.

b. excess NADH inhibits the TCA cycle, which then backs up glycolysis... no ATP --> death.

c. Same as Rotenone
a. What is carboxin?

b. What is 2-Thenoyltriflouroacetone?

c. So why would knocking out electron entry into complex to also knock out the TCA cycle?
a. It is an inhibitor of complex II.

b. same as above.

c. succinate backs up and stops the TCA cycle.
a. what is Antimycin A1?

b. why is this more serious?
a. Complex III inhibitor.

b. block both complexes I and II.
how many moles of protons does it take to make one ATP?
~3
which of the Fo subunit (a,b,c) is located in the membrane?
C
What part of the F0-F1 ATP synthase makes the ATP?
F1
Which F0-ATP synthase subunit spins and spits out the proton?

Which F1 ATP synthase subunit is responsible for making the ATP?
gamma
Aspartic acid drives the process of churning out the protons across a hydrophobic membrane, however, aspartic acid is negatively charged.

How do you get aspartic acid to go into the membrane?

What causes the conformational change in ATP synthase?
A proton - A proton (aspatic acid)