Oxidative Phosphorylation

Question 1

How is NADH moved ?

Answer 1

1. Glycerol 3-phosphate shuttle
2. Malate-aspartate shuttle. Put the electrons onto malate to transport them into the matrix.

Question 2

What is standard reduction potential?

Answer 2

E°
A measure of a compounds affinity for electrons.
Oxidising potential

Question 3

How do you calculate Gibbs free energy ?

Answer 3

Gibbs= -n x F x deltaE°
N is number of electrons transferred

Question 4

How much enegry does ATP require to from from ADP ?

Answer 4

30.5 kj/mol

Question 5

What is the name for complex I in the ETC ?

Answer 5

NADH-CoQ Oxidoreductase

Question 6

What is the name for complex III in the ETC ?

Answer 6

CoQ-Cytochrome c Oxidoreductase

Question 7

What is the name for complex IV in the ETC ?

Answer 7

Cytochrome c Oxidase

Question 8

What is another name for Coenzyme Q ?

Answer 8

Ubiquinone

Question 9

How does complex I function ?

Answer 9

1. NADH donates 2 electrons to complex I
2. Electrons are passes through FMN (flavin mono-nucleotide) and iron-sulphur (x6) clusters
3. These electrons reduce Coenzyme Q to ubuquinol (QH2)
   Also pumps 4 protons into the inter membrane space.

Question 10

What is Coenzyme Q ?

Answer 10

It is a lipid based electron carrier that moves freely within the mitochondrial inner membrane

Question 11

How does complex III function ?

Answer 11

1. Accepts electrons from ubiquinol (QH2)
2. Transfers the electrons to cytochrome c
3. Via Fe-S cluster and then either cytochrome b or chytochrome c1
   Also pumps 4 protons into the inter membrane space.

Question 12

What is cytochrome c ?

Answer 12

A mobile electron carrier protein.
It carries electrons from Complex III to complex IV

Question 13

What is the function of complex IV ?

Answer 13

1. Accepts electrons from cytochrome c
2. Transfers them to O2, the final electron acceptor
3. Oxygen combines with electrons and protons to form H2O
   Also pumps 2 protons into the inter membrane space.

Question 14

What is the name for complex II ?

Answer 14

Succinate-Coenzyme Q Oxidoreductase

Question 15

What is the function of complex II ?

Answer 15

Transfers electrons from FADH2 to Coenzyme Q, forming ubiquinol.
It is also part of the Krebs cycle.

Question 16

What is the efficiency of the ETC ?

Answer 16

40%

Question 17

What are reactive oxygen species (ROS) ?

Answer 17

They are generated during electron transport when electrons leak from Complex I or III and react with oxygen, which leads to formation of superoxide.

Question 18

Defense against ROS

Answer 18

1. Superoxide dismutase
2. Catalase. 2H2O2 to O2 + 2H20

Question 19

What does rotenone do ?

Answer 19

Inhibits NADH-CoQ Oxidoreductase

Question 20

Describe chemiosmosis

Answer 20

1. The ETC pumps protons from the matrix into the inter membrane space, creates a chemical and electrical gradient
2. These gradients form a proton motive force
3. Protons flow back into the matrix through ATP synthase (Complex V)
4. This drives the phosphorylation of ADP to ATP

Question 21

Describe the structure of ATP synthase

Answer 21

Alpha- binds ATP/ADP
Beta- catalytic site for ATP synthesis
C unit- rotates when proteins bind