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Flashcards in Electron Transport Chain Deck (42)
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1
Q

What is name of Coenzyme Q?

A

Ubiquinone

2
Q

The ______is a supramolecular complex involving complexes I, II, and III.

A

Respirasome

3
Q

ATP synthesis is coupled to electron transport via a ________ across the mitochondrial membrane.

A

Proton gradient

4
Q

Examples of inhibitors of ATP synthase

A

Oligomycin, dicyclohexylcarbodiimide

5
Q

Example inhibitors of Complex I

A
  1. Rotenone
  2. Amytal
6
Q

_______cycle shuts down if no ATP synthesis occurs

A

TCA

7
Q

Where do the electrons donated to Coenzyme Q go?

A

Complex III (Q- Cytochrome C Oxidoreductase)

8
Q

Example inhibitors of Complex IV

A

CN-, N3- (azide), CO

9
Q

Example of an uncoupling protein

A

UCP-1 (thermogenin)

10
Q

Final electron acceptor

A

O2

11
Q

There are no direct transporters for ____, ____, and ______.

A

NADH, acetyl CoA, and Oxaloacetate

12
Q

Example inhibitors of Complex III

A

Antimycin A

13
Q

Malate-aspartate shuttle

A
  1. Donates electrons from NADH to Complex I
  2. Involves the transport of malate/a-ketoglutarate and aspartate/glutamate
14
Q

Complex IV

A
  1. Cytochrome c oxidase
  2. Pumps 2 protons
15
Q

Complex III

A
  1. Q-cytochrome c oxidoreductase
  2. Receives electrons from Co enzyme Q
  3. Pumps 4 protons
  4. Donate electrons to Cytochrome C
16
Q

Glycerol-3-phosphate shuttle

A
  1. Shuttles electrons from FADH2
  2. Donates electrons to Q
  3. Allows transport against a NADH gradient
  4. Prevent in muscle
17
Q

How do the charged ATP and ADP ions exit and enter matrix?

A

Via the ATP-ADP Translocase

18
Q

Electron transport _____ energy; ATP synthesis ____ energy

A

Releases; Requires

19
Q

Inhibition of which components of the electron transport chain will stop ETC.

A

ATP-ADP translocase and ATP synthase

20
Q

Where do electrons from Cytochrome C go?

A

O2

21
Q

Which ion is essential to ETC?

A

Fe

22
Q

Which complex contains a heme group that does not receive electrons but protects against formation of reactive oxygen species (ROS)?

A

Complex II (succinate- Q reductase)

23
Q

Q pool consists of ___ and ____

A

Q and QH2

24
Q

Examples of inhibitors of ATP-ADP translocase

A

Atractyloside , bongkrekic acid

25
Q

Some organisms can uncouple electron transport from ATP synthesis to generate_____.

A

Heat

26
Q

_______ and ATP synthesis are usually tightly coupled.

A

Respiratory Chain

27
Q

Complex II

A
  1. Succinate- Q reductase
  2. Receives electrons from FADH2
  3. Does not pump electrons
  4. Contains flavoprotein succinate dehydrogenase
  5. Transfers electrons to Coenzyme Q
28
Q

Complex 1

A
  1. NADH-Q oxidoreductase
  2. Receives electrons from NADH
  3. Pumps four protons
  4. Transfers electrons to coenzyme Q
  5. Contains Flavin mononucleotide
29
Q

Chemical uncoupler example

A

2,4- dinitrophenol

30
Q

Brown adipose tissue

A

a. Rich in mitochondria

b. Contains uncoupling proteins
c. Protons allowed to flow back down into gradient back into matrix
d. ATP disrupted

31
Q

Components of Electron Transport Chain

  • Electrons passed down chain in order of increasing ________ potential—highly __________process
  • Energy released ultimately fuels synthesis of ________
  • Three large complexes that pump electrons

–Complex I: __________

–Complex III: ______________

–Complex IV: __________

•Complex II:_______________

–Contains ______________

–Does not pump protons

  • Electron carriers Coenzyme Q (ubiquinone) and cytochrome c
  • The ____________ is a supramolecular complex involving complexes I, II and III
  • Ultimate e- acceptor is_________
A

reduction; exergonic

ATP

NADH-Q oxidoreductase

Q-cytochrome c oxidoreductase

cytochrome c oxidase

succinate-Q reductase

flavoprotein succinate dehydrogenase

respirasome

oxygen

32
Q

NADH-Q Oxidoreductase (Complex I, or NADH Dehydrogenase)

  • Accepts electrons from _____________; donates to ___________
  • The reaction:
  • Pumps __________ protons
  • 2 protons used to form__________

Source of NADH: ____________, ____________, and _________________

A

NADH; Q

Four

QH2

TCA cycle, fatty acid b-oxidation, amino acid catabolism

33
Q

Complex II (Succinate-Q reductase complex)

  • Contains TCA cycle flavoprotein succinate dehydrogenase
  • Pair of e-’s passed from flavoprotein sequentially to 3 Fe-S centers, then to Q
  • Irons cycle between +2 (reduced) and +3 (oxidized)
  • Contains heme group (heme b) that does not receive electrons, but protects against formation of ____________
  • Does not pump protons
  • Receives e-’s from the _____________ or ____________
A

ROS

flavoproteins acyl-CoA dehydrogenase; glycerol-3-phophate reductase

34
Q

•ATP synthesis is coupled to e- transport via a ____________ across the mitochondrial _____________

A

proton gradient;inner membrane

35
Q

Role of Proton Gradient is to RELEASE ATP Formed on ________ of F1

•Observation from isotope exchange experiments: enzyme-bound ATP readily formed in absence of __________

–Gradient not needed to synthesize ATP

  • Why is ATP synthesis completely reversible?__________________
  • Role of gradient is not to from ATP but to drive its __________

Coupling between respiratory chain and ATP Synthesis is____________

A

b Subunit

proton gradient.

ATP synthase binds ATP more tightly, stabilizing ATP relative to ADP, shifting equilibrium

release

“obligatory”

36
Q

ATP Synthase Nucleotide Binding Sites Not Equivalent

•3 b subunits, so 3 active sites (only _______ is catalytically active)

–At any given moment, sites not equal:

  • T: tight (_______________)
  • O: open (____________)
  • L: loose (__________)
  • Rotation of g subunit, driven by _______ force, drives interconversion of sites
  • No two sites ever in same conformational form
  • ATP can be synthesized and released by driving rotation of ________subunit in correct direction
A

b

binds ATP very tightlycan bind or release ADP or ATP

binds ADP, Pi

proton motive

g

37
Q

How does proton flow through F0 drive rotation of the g subunit?

  • The F0 “a” subunit is _____________while the “c” subunits form a membrane-spanning ring that can ____________
  • “a” subunit contains two __________ half-channels that do not span the membrane

–Each half-channel interacts with one “c” subunit

–____________ residue in center

  • In proton-rich environment (_________side), proton will enter ½-channel and bind to Asp-61
  • “c” subunit then moves in a circle until Asp-61 is in proton-poor environment (_________) of other ½-channel—H+ released to matrix side
  • Movement of protons through ½-channels powers rotation of c-ring
  • Each proton moves across membrane by “riding around” –like a merry-go-round—on the c-ring
  • Important: c-ring is tightly linked to ____ and ___subunits
A

stationary (stator)

rotate (rotator)

hydrophobic

Aspartic acid

cytoplasmic

matrix

g; e

38
Q

Shuttles (Transporters, Carriers)

•How do electrons from cytoplasmic NADH enter e- transport chain?

–Inner membrane impermeable to ____________

–Glycerol-3-phosphate shuttle (prevalent in ________)

  • mitochondrial glycerol-3-phosphate dehydrogenase (uses _______)
  • Present on outer_____________surface of inner membrane
  • Donates electrons to_______
  • “P/O ratio:” Only __________molecules of ATP formed per e- pair
  • Allows transport against an _____ gradient

–Malate-aspartate shuttle (prevalent in ________ and __________)

  • Results in movement of pair of electrons from NADH across membrane into matrix—donates e-’s to complex _______
  • “P/O ratio:” _______ molecules of ATP formed per e- pair

–Malate-aspartate and glycerol-3-phosphate shuttles operate only under _______ conditions

•How does ATP4- exit, and how do ADP3- and phosphate enter, matrix? How many protons are required?

________________

A

NADH

muscle

FADH2

(cytoplasmic)

Q

1.5

[NADH]

heart; liver

I

2.5

aerobic

–Via the ATP-ADP translocase and the phosphate translocase; one

39
Q

•No direct transporters for __________, __________, and __________

A

NADH, acetyl-CoA and oxaloacetate

40
Q

Respiratory Chain and ATP Synthesis Usually Tightly Coupled

  • ___________ moles of ATP made per mole of glucose
  • ETC and ATP synthesis usually tightly coupled

–Rate of flow dependent on _________, ________, _________

–Likewise, TCA cycle shuts down if no ATP synthesis occurs

–Rates of ETC and TCA cycle regulated by rate of ATP synthesis—based on need for energy

•Some organisms can uncouple e- transport from ATP synthesis to generate________

–Brown adipose tissue

  • Rich in mitochondria
  • Contains lots of ________ protein
  • Protons allowed to flow down gradient, back into matrix

–__________ synthesis disrupted

A

Thirty

ADP, Pi, and O2

heat

uncoupling

ATP

41
Q

Inhibitors of OXPHOS

•Inhibition of e- transport chain

–___________ and __________: block e- flow through complex I (but flow thru II possible)

–_________: blocks flow through complex III

–_______, _________, and __________: inhibit cytochrome oxidase

  • Inhibition of ATP synthase by _________ and ___________
  • Example of chemical uncoupler:_____________

–e- transport can proceed, but ATP synthesis cannot

•Inhibition of ATP-ADP translocase by _________ and ______________

A

Rotenone, amytal

Antimycin A

CN-, N3- (azide), CO

–Oligomycin, dicyclohexylcarbodiimide

2,4-dinitrophenol

–Atractyloside, bongkrekic acid

42
Q
A