L15: Oxidative Phosphorylation

Question 1

Define prosthetic groups

Answer 1

Non-proteins that attach to proteins to assist them

Question 2

Components of the ETC

Answer 2

1) Proteins/protein complex embedded in the inner mitochondrial membrane containing prosthetic groups

2) Non-protein bound mobile element, CoQ

Question 3

Example of H acceptors (carry electrons)

Answer 3

Flavins & Ubiquinone

Question 4

1 mononucleotide & 1 dinucleotide within the ETC

Answer 4

FMN: Flavin mononucleotide
FAD: Flavin adenine dinucleotide

Question 5

How does FMN & FAD differ?

Answer 5

R groups

Question 6

What are cytochromes?

Answer 6

Proteins containing haem and carry an electron on the Fe2+ iron

Question 7

What do iron-sulphur proteins contani?

Answer 7

Fe-S clusters anchored via the side chain of cysteine residues

Question 8

3 features of ubiquinone (CoQ)

Answer 8

1) Not bound to protein
2) Freely mobile in the inner mitochondrial membrane
3) Transfers electrons from Complex I & II of ETC to Complex III

Question 9

What is redox potential a measure of?

Answer 9

Electron affinity of a molecule

Question 10

What happens if redox potential is more negative?

Answer 10

More likely a molecule is to pass on electrons

Question 11

What happens if redox potential is more negative?

Answer 11

More readily a molecule will accept electrons

Question 12

How does stepwise breakdown release energy?

Answer 12

In useable small ‘packages’

Question 13

What is energy released by electron transport used for?

Answer 13

To transport protons from the matrix to the intermembrane space

Question 14

Which complex of the ETC does not pump protons?

Answer 14

Complex II

Question 15

Why doesn’t Complex II pump protons?

Answer 15

Difference in redox potential between FAD & Q does not provide enough energy for transfer of protons across inner membrane

Question 16

How do protons creating a rotary motion when flowing ‘through’ ATP synthase?
F0 & F1

Answer 16

1) F0 spins as H+ passes through
2) F1 dosn’t spin, held stationary by a ‘stator’

Stator prevents rotation of F1 subunit

Question 17

2 main subunits of ATP synthase

Answer 17

F0 & F1

Question 18

What is the F0 subunit of ATP synthase?

Answer 18

Embedded in the inner membrane & rotates as protons flow ‘through’

Question 19

Which complex is ATP synthase?

Answer 19

Complex V

Question 20

Name for coupling of ATP synthesis to electron transport

Answer 20

Oxidative phosphorylation (OXPHOS)

Question 21

What does oxidative mean in OXPHOS?

Answer 21

Each component of the ETC is oxidised as they pass electrons

Question 22

What does phosphorylation mean in OXPHOS?

Answer 22

ADP is phosphorylated using Pi to create ATP

Question 23

Role of an inhibitor of an ETC complex

Answer 23

• Reduces transfer of electrons to/from that complex
• Reduces ATP synthesis
• Lead to production of damaging radicals

Question 24

What does uncoupling agents do in the inner mitochondrial membrane?

Answer 24

Create channels to be permeable to protons