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Principles: biochemistry > Oxidative Phosphorylation > Flashcards

Oxidative Phosphorylation Flashcards

1
Q

From one glucose molecule, the reactions of glycolysis, pyruvate dehydrogenase complex, and the TCA cycle produce

__ NADH + 10 H+
__ FADH2

Each one of them carries __ high-energy electrons

A

10 NADH + 10 H+
2 FADH2

two

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2
Q

essence of oxidative phosphorylation

  1. Electrons from NADH and FADH2 are used to reduce___ to ___
  2. Their energy is used to pump ___ from the mitochondrial ___ to the________ space
  3. __ decreases in______ space, increases in the ___
  4. _____ flow back across the membrane, following their concentration gradient
  5. Energy of __ flow is used to phosphorylate __ to ____
A
  1. Electrons from NADH and FADH2 are used to reduce O2 to H2O
  2. Their energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space
  3. pH decreases in intermembrane space, increases in the matrix
  4. Protons flow back across the membrane, following their concentration gradient
  5. Energy of proton flow is used to phosphorylate ADP to ATP
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3
Q
  • During glycolysis, __ NADH are formed in the cytoplasm
  • NADH cannot cross the ____ _____ _____
  • It cannot be re-oxidised to NAD+ directly using the electron transport chain
  • The _____-_-_____ and ____-______ shuttles overcome this problem
A
  • During glycolysis, 2 NADH are formed in the cytoplasm
  • NADH cannot cross the inner mitochondrial membrane
  • It cannot be re-oxidised to NAD+ directly using the electron transport chain
  • The glycerol-3-phosphate and malate-aspartate shuttles overcome this problem
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4
Q

how the glycerol-3-phosphate and malate-aspartate shuttle works:

  1. NADH from glycolysis is used to generate ____ from _____ in cytosol
  2. ___ transporters transfer ____ to mitochondrial ____.
  3. ____ conversion to
    _____ in TCA cycle
    generates ____ in addition to the malate that arises from Fumarate

so at the step where malate is converted to oxalacetate in the TCA cycle there is increased yield of NADH at this step as there is glycolytic yield and TCA yield

A
  1. NADH from glycolysis is used to generate malate from oxaloacetate in cytosol
  2. malate transporters transfer malate to mitochondrial matrix.
  3. malate conversion to
    oxaloacetate in TCA cycle
    generates NADH in addition to the malate that arises from Fumarate

IF YOU ARE STUCK _ LOOOK AT THE SLIDE, you understood it last time

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5
Q

In oxidative phosphorylation, the electron transfer potential of NADH+ and FADH2 is converted into the _____ ___ ____ of ___

Phosphoryl transfer potential can be measured by the ____ _____ change, ___, for the _____ of ATP

Electron transfer potential is measured by the-____ _____ (or reduction potential),___, of a compound

A

In oxidative phosphorylation, the electron transfer potential of NADH+ and FADH2 is converted into the phosphoryl transfer potential of ATP

Phosphoryl transfer potential can be measured by the free energy change, ΔGo’, for the hydrolysis of ATP

Electron transfer potential is measured by the redox potential (or reduction potential), E’o, of a compound

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6
Q
  • The standard redox potential E’o of a (reduced) substance X is a measure for how readily X donates an electron (in comparison with H2)
    X- → X + e-
  • A negative E’o means that the reduced form of X has a _____ affinity for electrons than __, a positive E’o means the opposite
  • The standard free energy change is proportional to the change in _____ ____ ____ and the number of ____ transferred
A

The standard redox potential E’o of a (reduced) substance X is a measure for how readily X donates an electron (in comparison with H2)
X- → X + e-
A negative E’o means that the reduced form of X has a lower affinity for electrons than H2, a positive E’o means the opposite
The standard free energy change is proportional to the change in standard redox potential and the number of electrons transferred

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7
Q

in oxidative phosphorylation one of the first steps is the reduction f O2 to H2O, what allows the electron to be carried from the NADH (itself being oxidised to NAD+)

A

the fact that the redox potential for NAD+/NADH is lower than that for 1/2 O2/H2O

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8
Q

The standard free energy change for the reaction
½ O2 + NADH + H+ → H2O + NAD+
is ΔGo’ = - 220.1 kJ/mol
The standard free energy change for the _____ of ATP is ΔGo’ = - 31.4 kJ/mol

A

hydrolysis

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9
Q

what is oxidative phosphorylation the coupling of?

A

coupling of respiration to ATP synthesis

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10
Q

oxidative phosphorylation consists of two stages, what are they

A
  1. electron transport

2. ATP synthesis

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11
Q

first stage of OP

  1. electron transport
    - electrons flow from NADH and FADH2 to O2
    - respiratory chain
    - energy is used to pump __out of the mitochondrial ____
A

electron transport
electrons flow from NADH and FADH2 to O2
respiratory chain
energy is used to pump H+ out of the mitochondrial matrix

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12
Q

second stage of OP

  1. ATP synthesis
    - _____ ____ of H+ across mitochondrial inner membrane
    - energy stored in this _____can be used to synthesise ___
A

ATP synthesis
electrochemical gradient of H+ across mitochondrial inner membrane
energy stored in this gradient can be used to synthesise ATP

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13
Q

Electron transport and ATP synthesis are catalysed by ____ ____ ___

A

Electron transport and ATP synthesis are catalysed by separate proton pumps

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14
Q

the electron transport part (respiratory chain) uses ___ multiunit complexes in the ___ ____ ___

A

4, inner mitochondrial membrane

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15
Q

Electrons from NADH enter at complex __

Electrons from FADH2 enter at complex __

A

Electrons from NADH enter at complex I

Electrons from FADH2 enter at complex II

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16
Q

complex __ is part of the TCA cycle

A

II

17
Q

Electrons are handed down from ___ to ___ redox potentials

A

Electrons are handed down from higher to lower redox potentials

18
Q

THE 4 COMPLEXES are involved in the process meaning ____ are ultimately transferred from ___ onto O2 to form H2O

A

Electrons are ultimately transferred from NADH and FADH2 onto O2 to form H2O

19
Q 
what are the 4 complexes 
I- 
II- 
III- 
IV-
A 
what are the 4 complexes 
I - NADH- Q oxidoreductase 
II- succinate -Q- reductase 
III - Q-cytochrome C oxidoreductase 
IV- cytochrome C oxidase
20
Q

what does coenzyme Q do?

A

it is a stable protein that is involved in transporting the electron - it is a portable protein

21
Q

what are the two accessory parts in the respiratory chain

A

coenzyme Q and cytochrome C

22
Q

what are cytochromes?

A

Cytochromes are proteins which contain a haem group as a functional co-factor
Haem contains an Fe(II) ion which can take up and release electrons

23
Q

how many H+ ions are pumped by complex 1, III and IV per NADH and H+ molecule

A

I- 4 are pumped
III- pumps 4
IV - pumps 2

ten in total

24
Q

how many electrons are transferred by 1 nadh and H+

A

2e- this makes sense betcause 2 e are required to reduce half O2 to H2O

25
Q

how do protons flow back through from intermembrane space to the matrix

A

ATP synthase

26
Q

what are the three components of ATP synthase?

A
  1. pore for protons
  2. i§ntermembrane domain (F0)
  3. matrix soluble domain known as F1
27
Q

atp synthase

a, b, α, β, and δ subunits form _____

A

stator

28
Q

c, γ, and ε subunits form ___-

A

rotos

29
Q

Electron transport chain can be inhibited at many stages

- ____ , ____ and ____ inhibit transfer of electrons to O2

A

cyanide, azide, and CO

30
Q

what is the P/O ratio

A

Number of molecules of inorganic phosphate (Pi) incorporate into ATP per atom of oxygen used

31
Q

what does the P/O depend on?

A

Depends on the substrate which is oxidised

32
Q

if NADH is oxidised to NAD+
P/O ratio = ___
if FADH2 is oxidised to FAD
P/O ratio =___

A

if NADH is oxidised to NAD+
P/O ratio = 2.5
if FADH2 is oxidised to FAD
P/O ratio = 1.5

33
Q

___ ____ _____ strongly influences theP/O ratio

A

uncoupling protein activity

34
Q

what does the uncoupling protein do?

A

‘generates heat by short-circuiting the mitochondrial battery’

35
Q

what does the final balance of ATP depend on? 2

A

Depends on precise values for the P/O ratio

Depends on which shuttle is used for transporting cytoplasmic NADH into the mitochondrial matrix

36
Q

1 glucose molecule yields __ to ___ ATP molecules

A

30-32

Principles: biochemistry (7 decks)

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