Terminal Respiration

Question 1

Where is most of the NADH and FADH2 made and by what process?

Answer 1

Mitochondria, by citric acid cycle and beta oxidation of fatty acids

Question 2

How does cytoplasmic NADH cross the mitochondrial membrane?

Answer 2

It can’t, instead it reduces dihydroxyacetone phosphate to produce Glycerol-3-phosphate. This passes its electrons onto FAD forming FADH2 which enters the electron transport chain, this process is called the glycerol phosphate shuttle

Question 3

How many protein complexes are in the electron transport chain?

Answer 3

4

Question 4

What happens in complex 1 after the NADH molecule is oxidised to give NAD+?

Answer 4

It passes the high energy e- to ubiquinone to give ubiquinol. Pumps H+ ions into the intermambrane space

Question 5

What does complex 2 oxidise to form ubiquinol?

Answer 5

FADH2

Question 6

What does complex 3 do?

Answer 6

Passes the e-‘s from ubiquinol to cytochrome C, giving two molecules of reduced cytochrome C per molecule of ubiquinol. Pumps 4 proteins into the inter-membrane space

Question 7

What does the 4th protein complex do?

Answer 7

Takes electrons from cytochrome C and passes them on to molecular O2 - Forms water (2 protons pumped to inter-membrane space)

Question 8

What is the name given to the turbine that can harness the energy in the proton gradient?

Answer 8

ATP Synthase

Question 9

Where are the protons moved to by the 4 protein complexes?

Answer 9

the inner mitochondrial membrane

Question 10

How is the energy of the proton motive force stored by ATPase?

Answer 10

By using the energy to synthesise ATP from ADP + Pi

Question 11

Describe the two parts of ATP synthase

Answer 11

F0 - Rotates. Membrane bound proton conducting sub-unit - 10 subunits
F1 - Protrudes into the mitochondrial matrix and acts as the catalyst for ATP synthesis

Question 12

What does the proton gradient drive (What step requires the most energy)?

Answer 12

The release of ATP and not the formation of ATP

Question 13

What are the different conformations of the beta sub-unit protein on the F1 protein?

Answer 13

ATP
ADP + Pi
Nothing bound

Question 14

How many protons are needed for each full rotation of the beta subunit

Answer 14

3, so therefore ATP synthase can make one molecule of ATP for every H+ ion it moves across the membrane and into the matrix

Question 15

What generates less ATP, FADH2 or NADH?

Answer 15

FADH2

Question 16

For every molecule of NADH, how many protons are pumped across the membrane?

Answer 16

10

Question 17

Why does NADH produce more ATP than FADH2

Answer 17

NADH passes through carrriers 1,3 and 4 whereas FADH2 feeds in at complex 2, meaning only two of the proton releasing proteins are used

Question 18

What are the last two products of respiration? (excluding ATP)

Answer 18

CO2 and H2O

Question 19

Which two processes are coupled?

Answer 19

Electron tranport (energy released when passing electrons along the terminal respiration system) and ATP synthesis

Question 20

Give an example of a disease caused by uncoupling and why it became uncoupled?

Answer 20

Malignant hyperthermia. Leaky mitochondrial membrane - proton gradient cannot be generated. Proton transport occurs but there is no synthesis of ATP uncouples electron transport and the electron transport chain. Muscle cells become damaged from excessive heat build up. Used in plants to generate heat

Question 21

Describe what facilitates the transport of protons from outside the inner membrane to the outside?

Answer 21

Thermogenin - Triggered by epinephrine