Oxidative Phosphorylation

Question 1

<p>What are the two stages in oxidative phosphorylation?</p>

Answer 1

<p>- Electron transport

| - ATP Synthesis</p>

Question 2

<p>From one glucose molecule, the reactions of...
- glycolysis
- pyruvate dehydrogenase complex
- TCA cycle
produce how many NADH + H and FADH2?</p>

Answer 2

<p>- 10 NADH + 10H+

| - 2 FADH2</p>

Question 3

<p>Each one of NADH + H+ and FADH2 carries how many high energy electrons?</p>

Answer 3

<p>2</p>

Question 4

<p>Steps of Oxidative Phosphorylation</p>

Answer 4

<p>- Electrons from NADH and FADH2 are used to reduce O2 to H2O

- Their energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space
- Protons flow back across the membrane, following their concentration gradient
- Energy of proton flow is used to phosphorylate ADP to ATP</p>

Question 5

<p>PH decreases in the \_\_\_\_\_\_\_\_\_\_ and increases in the \_\_\_\_\_\_\_\_\_\_</p>

Answer 5

<p>- membrane space

| - matrix</p>

Question 6

<p>NADH cannot cross the...</p>

Answer 6

<p>inner mitochondrial membrane</p>

Question 7

<p>NADH cannot be re-oxidised to NAD+ directly using ....</p>

Answer 7

<p>the electron transport chain</p>

Question 8

<p>What overcomes NADH being unable to be re-oxidised using the electron transport chain?</p>

Answer 8

<p>The glycerol-3-phosphate and malate-aspartate shuttle</p>

Question 9

<p>During glycolysis, how many NADH are formed in the cytoplasm?</p>

Answer 9

<p>2 NADH</p>

Question 10

<p>How is the phosphoryl transfer potential measured?</p>

Answer 10

<p>measured by the free energy change, (delta G0) for the hydrolysis of ATP</p>

Question 11

<p>How is the electron transfer potential measured?</p>

Answer 11

<p>measured by the redox potential (or reduction potential), E0 of a compound</p>

Question 12

<p>What is the standard redox potential E0 of a reduced substance?</p>

Answer 12

<p>A measure of how readily the substance donates an electron</p>

Question 13

<p>What does a negative E0 mean?</p>

Answer 13

<p>the reduced form of the substance has a lower affinity for electrons than H2</p>

Question 14

<p>What does a positive E0 mean?</p>

Answer 14

<p>the reduced form of the substance has a higher affinity for electrons than H2</p>

Question 15

<p>Standard free energy change is proportional to...</p>

Answer 15

<p>the change in standard redox potential and the number of electrons transferred</p>

Question 16

<p>Oxidative phosphorylation is the coupling of...</p>

Answer 16

<p>respiration to ATP synthesis</p>

Question 17

<p>Electron transport chain occurs when electrons flow from</p>

Answer 17

<p>NADH and FADH2 to O2</p>

Question 18

<p>Electron transport - respiratory chain</p>

Answer 18

<p>- Electrons from NADH enter at complex I, electrons from FADH2 enter at complex II (TCA cycle)

- Electrons are handed down from higher to lower redox potentials
- Transferred onto O2 to form H2O</p>

Question 19

<p>Transfer of electrons through the respiratory chain is coupled to what?</p>

Answer 19

<p>coupled to H+ transport from mitochondrial matrix to intermembrane space</p>

Question 20

<p>Electron transport and ATP synthesis are catalysed by what?</p>

Answer 20

<p>Catalysed by separate proton pumps</p>

Question 21

<p>What is a cytochrome?</p>

Answer 21

<p>Proteins which contain a haem group as a functional co-factor</p>

Question 22

<p>Haem contains an Fe(II) ion which can do what?</p>

Answer 22

<p>Take up and release electrons</p>

Question 23

<p>Transfer of electrons through the respiratory chain is coupled to...</p>

Answer 23

<p>transport of H+ from the mitochondrial matrix to the intermembrane space</p>

Question 24

<p>How many out of the four respiratory complexes pump H+?</p>

Answer 24

<p>3/4</p>

Question 25

<p>Electrochemical Gradient Mechanism</p>

Answer 25

<p>- more protons in the intermembrane space than in the matrix

- forms an electrical field with the matrix side more negative
- protons want to flow back into the matrix
- flow back into the matric is coupled to ATP synthesis</p>

Question 26

<p>The respiratory chain pumps protons into where?</p>

Answer 26

<p>The intermembrane space</p>

Question 27

<p>After being pumped into the intermembrane space by the repiratoy chain, protns flow back through...</p>

Answer 27

<p>ATP synthase (two seperate proton pump systems)</p>

Question 28

• F1 subunit protrudes into mitochondrial matrix
• F0 subunit is a hydrophobic complex in the inner membrane
• Flow of portons turns the rotor
• Conformational changes lead to ATP synthesis

Answer 28

ATP synthase

Question 29

Ways the electron transport chain can be inhibited

Answer 29

• cyanide, azide and CO inhibit transfer of electrons to O2
• No proton graident can be formed
• No ATP can be synthesised

Question 30

What is an uncoupling protein (UCP)?

Answer 30

a mitochondrial inner membrane protein that is a regulated proton channel or transporter

Question 31

Oxidation of food stuffs to acetyle-CoA produces some ______ and releases _______

Answer 31

• ATP

- Electrons

Question 32

Electrons are accepted by organic co-factors and transferred to…

Answer 32

the respiratory chain (recycles the co-factors)

Question 33

Energy of the proton gradient is used to drive what process?

Answer 33

ATP synthase

Question 34

What is the P/O ratio used for?

Answer 34

As a measurement of the coupling of ATP synthesis to electron transport