Oxidative Phosphorylation

Question 1

What is oxidative phosphorylation?

Answer 1

High energy electrons (carried by NADH and FADH2) are used to reduce O2 to H2O

Question 2

Their energy is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space, what happens to the protons after this?

Answer 2

Protons flow back across the membrane, following thier conc. gradient
Energy of proton flow is used to phosphorylate ADP to ATP

Question 3

What happens to the electron flow in the respiratory chain?

Answer 3

Flow down the ECC from negative to more positive redox potential

Question 4

What happens to big jumps in redox potential?

Answer 4

Equates to big changes in G. These chnages in free energy can be harnessed

Question 5

How many mitochondria exist in liver cells?

Answer 5

1000-2000

Question 6

What two stages are there in oxidative phosphorylation?

Answer 6

Electron transport and ATP synthesis

Question 7

What happens in the electron transport?

Answer 7

• Electron flow from NADH and FADH2 to O2
• Respiratory chain
• Energy is used to pump H+ out of the mitochondrial matrix

Question 8

What happens in ATP synthesis?

Answer 8

• Electrochemical gradient of H+ across mitochondrial inner membrane
• Energy stored in this gradient can be used to synthesise ATP

Question 9

How is the electron transport and ATP synthesis catalysed?

Answer 9

Separate proton pumps

Question 10

How many multisubunit complexes are ther ein the ECC?

Answer 10

4

Question 11

What occurs within these 4 complexes in the ECC?

Answer 11

Electrons from NADH enter at complex 1
Electrons from FADH2 enter at complex 2
Electrons are handed down from higher to lower redox potentials

Question 12

Is complex 2 in the ECC a proton pump?

Answer 12

No

Question 13

What step that occurs in the ECC causes us to breathe?

Answer 13

electrons are ultimately transferred onto O2 to form H2O

Question 14

Is Cytochrome c soluble?

Answer 14

Yes

Question 15

More protons are in the intermembrane space than in the membrane what does this lead to?

Answer 15

Forms an electrical field with the matrix side more negative
Meaning protons want to flow back into the matrix

Question 16

What is the flow of electrons back into the matrix coupled with?

Answer 16

ATP synthesis

Question 17

What is ATP synthase also called?

Answer 17

Mitochondral ATPase

F1F0ATPase

Question 18

Where does the F1 subunit protrude into?

Answer 18

The mitochondrial matrix

Question 19

Where is the F0 subunit located?

Answer 19

Hydrophobic complex in the inner membrane

-contains the proton channel

Question 20

What do conformational changes in the ATP synthase pump lead to?

Answer 20

ATP synthesis

Question 21

What happens when the protons flow through the ATP subunit?

Answer 21

they rotate

Question 22

What two components exist within the ATP synthase subunit?

Answer 22

Rotating component

Static component

Question 23

What is the P/O ratio?

How is it calculated?

Answer 23

A measurement of the coupling of ATP synthesis to electron transport

Number of molecules of the inorganuc phosphate (Pi) incorporate into ATP per atom of oxygen reduced

Question 24

What is the P/O ratio for NADH when oxidised to NAD+ AND FADH2 when oxidised to FAD

Answer 24

NADH- 2.5

FADH2- 1.5

Question 25

How many cycles does the TCA cycle run?

Answer 25

2

Question 26

OXPHOS diseases is a common egenerative disease that is due to what?

Answer 26

Mutations in the mitochondrial or nuclear DNA caused by oxidative phophorylation

Question 27

Where does OXPHOS disease occur and why does pathology become worse with age?

Answer 27

Appears in tissues with highest ATP demands- nervous sytem, heart, skeletal muscle, kidney

With age, spontaneous mutations accumulate, at some point not enough ATP can be generated