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MABS Biochemistry > Electron Transport Chain > Flashcards

Electron Transport Chain Flashcards

1
Q

B.Identify the components of the electron transport chain (ETC). Recognize which components are integral versus peripheral proteins and lipid-bound molecules versus small metabolites.

A 
●	Complex 1
○	Lipid-bound molecule
○	NADH: CoQ oxidoreductase
●	Complex II
○	Peripheral 
○	Succinate dehydrogenase
●	Complex III
○	Lipid-bound molecule
○	Cytochrome b-c1 complex
●	Complex IV
○	Lipid-bound molecule
○	Cytochrome c oxidase
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2
Q

C.Relate the reaction of NADH (hydride transfer) at Complex I (NADH dehydrogenase) to start the electron transport chain reaction.

A

● NADH is oxidized to NAD+
● 4 H+ are shuttled to the intermembrane space
● Complex one transfers electrons to coenzyme Q
● 10 H+ are transported per 1 NADH oxidized

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3
Q

D.Relate the reaction of FADH2 at Complex II to start the electron transport chain reaction.

A

● Complex II is a peripheral protein
● Succinate dehydrogenase (succinate → fumerate)
● Electrons come from succinate and go to coenzyme Q, bypassing complex I
● Does not transfer H+ across gradient
● Fe-S centers and FAD flavoproteins
● FADH2 does not give off as many electrons because it is not as good of a donor as NADH

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4
Q

G.For each step of the ETC, identify how electrons move from one species to the next, and recognize which species becomes reduced and what becomes oxidized as the electrons move.

A

● Complex 1
○ NADH is oxidized to NAD+ (red)
○ The complex with its electrons is now a reduced complex
○ 4 H+ are pumped out to intermembrane space
○ The electrons are transported in CoQ making the complex oxidized
○ 10 H+ are transported per 1 NADH oxidized
● Complex II
○ FADH2 is oxidized to FAD
○ The complex with its electrons is now a reduced complex
○ No H+ are transported into intermembrane space
○ 6 H+ are transported per 2 electrons entering ETC from complex II: 1.4 ATP formed
○ The electrons are given to CoQ and makes the complex oxidized
● Complex III
○ Gets 2 electrons from CoQ, complex is now reduced
○ CoQ protons are released into the inter membrane space
○ Transfers those 2 electrons to cytochrome c, complex is now oxidized
○ 2 additional H+ are transported (4 H+ total transported)
● Complex IV
○ Accepts 2 electrons from cytochrome c, complex is now reduced
○ 2 H+ are transported into intermembrane space
○ Electron is transferred to O2 forming H20, complex is now oxidized
○ Called the “terminal oxidase” because this is where ETC ends

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5
Q

H.Recognize and identify which ETC integral proteins pump protons across the inner mitochondrial membrane from the matrix to cytosolic side.

A

● Complex I: 4 H+ are pumped out per pair of electrons that pass through
● Complex II: no protons are passed through
● Complex III: 4 H+ are pumped out per pair of electrons that pass through
● Complex IV: 2 H+ are pumped out per pair of electrons that pass through

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6
Q

I.Recognize and interpret the influence of the proton gradient on the activity of the electron transport chain and vice versa.

A

● Proton gradient is the pumping of protons across the membrane trying to get an equal charge on each side
● ATP synthase uses the proton gradient as an energy source to synthesize ATP
● ETC creates the proton gradient and MUST have O2, supply of electrons, and intact inner mitochondrial membrane
● More ATP produced? Proton gradient runs down, ETC activated
● Less ATP used? Proton gradient not used so ETC slows down

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7
Q

A.Compare the mitochondrial content of different tissues and relate this characteristic to the function of the particular tissue (skeletal muscle versus cardiac muscle, parietal cells, etc.).

A
  • Cardiac and slow twitch muscle: lots of mitochondria, lots of oxygen consumption, lots of aerobic ATP production, steady, constant work.
  • Fast twitch skeletal muscle: less mitochondria, more reliance on anaerobic ATP production by glycolysis, can utilize aerobic ATP production. Quick energy bursts, rapid ATP use then time for tissue recovery.
  • Red Blood Cells: no mitochondria, no aerobic energy production, but energy needs are fairly light compared to other cell types.
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8
Q

cardiac and slow twitch muscles mitochondrial content?

A

lots of mitochondria, lots of oxygen consumption, lots of aerobic ATP production, steady, constant work.

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9
Q

Fast twitch skeletal muscle mitochondrial content?

A

less mitochondria, more reliance on anaerobic ATP production by glycolysis, can utilize aerobic ATP production. Quick energy bursts, rapid ATP use then time for tissue recovery.

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10
Q

Red Blood Cells mitochondrial content?

A

no mitochondria, no aerobic energy production, but energy needs are fairly light compared to other cell types.

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11
Q

ATP in the muscle at any given time can take us how far?

A

40 yds

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12
Q

Phosphocreatine can take us how far?

A

120 yds (covered later: regenerates ATP from ADP)

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13
Q

Glycogen can take us how far?

A

1400 yds (anaerobically - Glycolysis…2 net ATP)

10 miles (aerobically - Glycolytic pyruvate to TCA)

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14
Q

Fat can us how far?

A

630 miles (aerobic ATP production)

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15
Q

where is the ETC located?

A

inner mitochondrial membrane

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16
Q

what produces acetyl CoA?

A

Glycolysis, fatty acid oxidation and the oxidation of amino acids

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17
Q

what does the TCA cycle oxidize?

A

acetate and produces reduced cofactors (NADH, FADH2) that carry electrons to the ETC.

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18
Q

where do the reduced cofactors of the TCA cycle gives their electrons?

A

to the ETC

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19
Q

what does the ETC create?

A

a proton gradient that drives the formation of ATP by the ATP synthase (oxidative phosphorylation).

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20
Q

what is the chemiosmotic Theory?

A

Electron transfer from NADH/FADH2 to O2 through the ETC creates a a proton concentration gradient, which serves as an energy source for ATP formation

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21
Q

what is the electron transport chain? what is the effect on oxygen? what is the effect of the passage of electrons through the chain?

A

a series of proteins and compounds that receive electrons from NADH and/or FADH2 generated by the TCA cycle and catabolic pathways; The ETC will transfer these electrons to molecular oxygen to form water; The passage of electrons through the chain release energy that is used to transport protons across the inner mitochondrial membrane and thereby maintain a large proton gradient.

22
Q

briefly describe the route of electrons through the ETC?

A 
NADH to
Complex 1 to
Coenzyme Q to
Complex 3 to
Cytochrome C to
Complex 4 to
Oxygen

high proton concentration in the intermembrane space and low on the inside, they come back via ATP synthase and that energy is used to produce ATP

23
Q

where does the TCA cycle occur? fatty acid oxidation?

A

both inside the mitochondrial matrix; fatty acid oxidation makes a lot of NADH(ETC) and acetyl CoA(TCA)

24
Q

where does the ETC cycle occur?

A

the inner mitochondrial membrane

25
Q

in the ETC, what is unique about Complex II?

A

its succinate dehydrogenase from TCA cycle, electrons removed and captured by flavin and fumarate comes off.

26
Q

what complexes do NADH and FADH2 bind?

A

NADH to complex 1 and FADH2 to Complex II

27
Q

describe coenzyme Q?

A

it can bind to complex I to receive electrons and can bind to complex II to pick up electrons

28
Q

what is unique of complex IV?

A

electron pass quickly and bind to molecular oxygen, splitting it to produce water

29
Q

what type of transport is used to shuttle protons out of the mitochondrial matrix?
how many are shuttled across complex I,II,IV, and ATP synthase?

A

active transport due to movement of electrons through the ETC; 4,4,2, 3

30
Q

what are the requirement for ATP synthesis?

A

10 H+ are transported per 1 NADH oxidized, 6 H+ are transported per 1 FADH2 oxidized.
3 H+ are required per ATP synthesized, and 1 H+ is required for import of 1 inorganic phosphate

31
Q

how many hydrogens are transported per 1 NADH oxidized? FADH2?

how many hydrogens are required per ATP synthesized and for the import of 1 inorganic phosphate? Water?

how many protons are needed to make 1 ATP?

A

10 H+ are transported per 1 NADH oxidized, 6 H+ are transported per 1 FADH2 oxidized

3 H+ are required per ATP synthesized, and 1 H+ is required for import of 1 inorganic phosphate

2 protons used to make water too

synthesis of 1 ATP molecule requires the movment of 4 H+: 3H+ needed to synthesize the ATP molecule + 1 H+ required to bring the needed Pi in = 4 H+ per ATP total.

32
Q

is there higher ADP inside or outside of the mitochondrial matrix?what about Pi?

A

outside and higher ATP concentration on the inside (ATP/ADP translocase); proton gradient to is used to bring in Pi (phosphate transporter)

33
Q

for every mole of NADH used for the ETC results in how many ATPs produced? FADH2? So how if we know there are 3 NADH molecules made from the TCA cycle then there is how much ATP made total?

A

2.5; 1.5; 7.5

34
Q

how many moles of ATP from every flavin?

A

Recall 4 H+ required to synthesize and transport 1 ATP: Therefore, for each FADH2 to 1.5 ATP formed for every flavin

35
Q

T/F, glycerol 3 phosphate dehydrogenase and succinate dehydrogenase both contribute their electrons to Coenzyme Q?

A

T

36
Q

what are the sources of electrons that go to coenzyme Q?

A

NADH dehydrogenase from complex I, succinate dehydrogenase from complex II, and other flavoproteins

37
Q

what is key about Complex I?

A

NADH delivers electrons to Complex I in the form of a hydride ion, H:-, as one single unit. Once bound, the hydride electrons are split and move through Complex one at a time through an internal Flavin then on through a network of Fe-S clusters to CoQ.

38
Q

what is key about Complex II?

A

like complex I except that
no protons are transported by complex II

FADH2 passes electrons to a chain of three Fe-S clusters

Electrons transferred on to CoQ forming CoQ(H2): electrons

No protons are transported into matrix during this process.

Flavins are hydrophobic and must be bound to proteins. Not mobile in the aqueous phase.

39
Q

what is Coenzyme Q?

A

comprised of quinone ring and has a semiquinone form and its reduced form.
its a Lipid soluble cofactor and resides in the inner mitochondrial membrane

40
Q

what is unique about coenzyme Q?

A

Freely diffuses between binding partners

Accepts 2 e- and 2 H+ in two single steps. Transfers electrons to complex III

Errors in this reaction can result in e- transfer to O2, forming superoxide, O2-

41
Q

what complex of the mitochondria uses the majority of oxygen we breath?

A

complex IV, remember that 2 H+ are transported

42
Q

what must be for complex IV to function?

A

molecular oxygen MUST be present for the electrons to move entirely through Complex 4 and out of the complex and for the 2 H+ to be transported. This gets the complex back to the oxidized state so it can receive two more electrons from cyt c in the next go round.

43
Q

what is the standard reduction potential?

A

the driving force behind why NADH gives away it electrons and so it how likely it is to give or take an electron, strong change in reduction potential from NADH to Coenzyme Q and through this to three, going from more negative to positive and so forth for complex IV as well

44
Q

the main regulator for the ETC is the____?

A

ATP synthase

45
Q

what are the forces of the ETC?

A

chemical(concentration) and voltage force moving in the same direction

46
Q

describe the effect on intermediated metabolism on the body after running?

A

demand for NADH is greater because ETC is asking for more because it needs to make more protons because ATP synthase needs this make more ATP

47
Q

what does NADH control? what does the proton gradient control? what controls the proton gradient?

A

TCA cycle; ETC; ATP synthase

48
Q

what is needed for the ETC to create the proton gradient?

A

O2
supply of electrons
intact inner mito membrane

49
Q

what uses the protein gradient as an energy source to synthesize ATP?

A

ATP synthase

More ATP produced? Proton gradient runs down, ETC activated
Less ATP used? Proton gradient not used so ETC slows down.

50
Q

A patient has stopped breathing. How will this affect the function of his Electron Transport Chain?

A. No effect: The ETC will continue as normal.
B. The ETC will be activated to compensate for the loss of O2.
C. The ETC will be inhibited due to a lack of O2.
D. The ETC will be inhibited due to a loss of TCA cycle function.
E. There will be additional loss of electrons from the ETC.

A

C. The ETC will be inhibited due to a lack of O2.

51
Q

A patient is exposed to carbon monoxide, which destroys the function of Complex IV in his mitochondria. How will this affect the function of his TCA cycle?

A. No effect: CO binds to ETC Complex IV
B. The TCA cycle will be activated to compensate
C. The TCA cycle will be inhibited as the ETC shuts down
D. The TCA cycle will no longer produce NADH for the ETC

A

C. The TCA cycle will be inhibited as the ETC shuts down

MABS Biochemistry (54 decks)

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