Oxidative Phosphorylation

Question 1

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

Answer 1

10 NADH + 10 H+
2 FADH2

two

Question 2

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 ____

Answer 2

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

Question 3

• 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

Answer 3

• 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

Question 4

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

Answer 4

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

Question 5

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

Answer 5

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

Question 6

• 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

Answer 6

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

Question 7

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+)

Answer 7

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

Question 8

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

Answer 8

hydrolysis

Question 9

what is oxidative phosphorylation the coupling of?

Answer 9

coupling of respiration to ATP synthesis

Question 10

oxidative phosphorylation consists of two stages, what are they

Answer 10

1. electron transport

2. ATP synthesis

Question 11

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 ____

Answer 11

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

Question 12

second stage of OP

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

Answer 12

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

Question 13

Electron transport and ATP synthesis are catalysed by ____ ____ ___

Answer 13

Electron transport and ATP synthesis are catalysed by separate proton pumps

Question 14

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

Answer 14

4, inner mitochondrial membrane

Question 15

Electrons from NADH enter at complex __

Electrons from FADH2 enter at complex __

Answer 15

Electrons from NADH enter at complex I

Electrons from FADH2 enter at complex II

Question 16

complex __ is part of the TCA cycle

Answer 16

II

Question 17

Electrons are handed down from ___ to ___ redox potentials

Answer 17

Electrons are handed down from higher to lower redox potentials

Question 18

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

Answer 18

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

Question 19

what are the 4 complexes 
I- 
II- 
III- 
IV-

Answer 19

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

Question 20

what does coenzyme Q do?

Answer 20

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

Question 21

what are the two accessory parts in the respiratory chain

Answer 21

coenzyme Q and cytochrome C

Question 22

what are cytochromes?

Answer 22

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

Question 23

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

Answer 23

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

ten in total

Question 24

how many electrons are transferred by 1 nadh and H+

Answer 24

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

Question 25

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

Answer 25

ATP synthase

Question 26

what are the three components of ATP synthase?

Answer 26

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

Question 27

atp synthase | a, b, α, β, and δ subunits form _____

Answer 27

stator

Question 28

c, γ, and ε subunits form ___-

Answer 28

rotos

Question 29

Electron transport chain can be inhibited at many stages | - ____ , ____ and ____ inhibit transfer of electrons to O2

Answer 29

cyanide, azide, and CO

Question 30

what is the P/O ratio

Answer 30

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

Question 31

what does the P/O depend on?

Answer 31

Depends on the substrate which is oxidised

Question 32

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

Answer 32

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

Question 33

___ ____ _____ strongly influences theP/O ratio

Answer 33

uncoupling protein activity

Question 34

what does the uncoupling protein do?

Answer 34

‘generates heat by short-circuiting the mitochondrial battery’

Question 35

what does the final balance of ATP depend on? 2

Answer 35

Depends on precise values for the P/O ratio | Depends on which shuttle is used for transporting cytoplasmic NADH into the mitochondrial matrix

Question 36

1 glucose molecule yields __ to ___ ATP molecules

Answer 36

30-32