Oxidative Phosporylation // Electron Transport Chain

Question 1

What is oxidative phosphorylation?

Answer 1

ATP is formed as a result of transfer of electrons from NADH or FADH to 02 by a series of electron carriers.

Question 2

How many of the ATP molecules are generated from complete oxidation of glucose to CO2 and H20?

Answer 2

26 out of the 30 ATP molecules were generated from complete oxidation.

Question 3

Why is the release of energy from the oxidation of FADH2 and NADH important?

Answer 3

This is important as it powered the production of ATP.

Question 4

What is the electron transport chain?

Answer 4

A series of membrane protein complexes in the inner membrane couple electron transport to H+ movement.

Question 5

What is the electron transport chain also known as?

Answer 5

The chemiosmotic part of the pathway.

Question 6

Explain what is a proton motive force.

Answer 6

This is when H+ ions are pumped from the matrix into the intermembrane space.
So is an electrochemical gradient of protons across a membrane.

Question 7

What does the proton motive force do?

Answer 7

The proton motive force powers ATP synthase and therefore, generates ATP.

Question 8

What are the 2 components which drive H+ in the same direction?

Answer 8

Chemical gradient = changes pH

Electrical gradient = changes electrical voltage

Question 9

What is the electron transport chain made of?

Answer 9

It’s made of 4 membrane protein complexes called I - IV.

Question 10

What is the Complex I NADH dehydrogenase?

Answer 10

It is an enzyme which is supposed to take off the two electrons off from NADH.

Question 11

What is Complex I also known as?

Answer 11

• NADH dehydrogenase

- NADH - Q oxidoreductase

Question 12

How many core subunits are essential and conserved in all species?

Answer 12

There are 14 core subunits.

Question 13

What are the 2 domains in Complex I?

Answer 13

• Hydrophhilic Domain

- Membrane Domain

Question 14

Explain the membrane domain.

Answer 14

Does not contain redox centres.

Pumps 4 H+ across membrane per 2e- donated by NADH.

Question 15

Explain the hydrophilic domain.

Answer 15

Contain redox cofactors.
NADH is oxidised to NAD+
The 2e- are passed to ubiquinone (Q) forming ubiquinol (QH2) at the membrane.

Question 16

What is Complex II?

Answer 16

It is an enzyme of the citric acid cycle.

Complex II’s enzyme is succinate dehydrogenase.

Question 17

What is Complex III (bc1 complex)?

Answer 17

Membrane contains a hoard of ubiquinol (QH2) which is reduced in Complex I and II.

Question 18

Explain the mechanism of Q cycle.

Answer 18

This is a cycle involving Complex III.
Complex III passes electrons from QH2 to another electron carrier known as cytochrome C.
4H+ ions are pumped across membrane as 2 electrons are passed from QH2 to CYT C.

Question 19

What are electron carriers used for?

Answer 19

Electron carriers are a way of moving electrons through the system.

Question 20

What is cytochrome C’s purpose?

Answer 20

Transfers the electrons from Complex III to Complex IV.

Question 21

Explain the basic traits of Cytochrome C.

Answer 21

Small and water soluble protein.
It’s found in intermembrane space of mitochondria.
Contains a haem cofactor too.

Question 22

Where is the ATP synthase normally found?

Answer 22

Found in mitochondria // chloroplasts in eukaryotes.

Question 23

How does ATP synthase work?

Answer 23

Uses energy from proton motive force to drive ATP synthesis.
Can also use ATP hydrolysis to generate a proton motive force.
The proton flow through ATP synthase leading to the production of ATP.

Question 24

What is the evidence for the rotation of the ATP synthase?

Answer 24

The F1 part of a bacterial ATP synthase was attached to a. solid surface and a fluorescent actin filament attached to the y subunit.
ATP was added to drive the enzyme in the backwards direction.

Question 25

What causes ATP synthesis?

Answer 25

Rotation of the y subunit within the alpha - beta subunits.