Protein control 5: Complex I

Question 1

What molecules are used as transient energy storage prior to the electron transport chain?

Answer 1

NADH and FADH2

Question 2

How many complexes in the electron transport chain (ETC) and how are they connected?

Answer 2

4 complexes connected by mobile electron carriers

Question 3

What is the function of ubiquinone (Coenzyme Q) in the ETC? Properties (oxidsed/reduced, location etc.)?

Answer 3

Acts as a mobile electron carrier
- can carry 1 or 2 electrons

Oxidised = ubiquinone, reduced = ubiquinol

Anchored to the membrane via hydrophobic isoprene tail

Question 4

What conditions must be met for ubiquinone to act as a 1 electron carrier?

Answer 4

When bound by protein which stabilises semiquinone radical

Question 5

What conditions must be met for ubiquinone to act as a 1 electron carrier?

Answer 5

When bound by protein which stabilises semiquinone radical

e.g. cytochrome bc1 complex

Question 6

Equation for oxidation/reduction of ubiquinone?

Answer 6

UQH2 UQ + 2H+ + 2e-

Question 7

REDUCTION POTENTIAL MATHS

Answer 7

needs writing up

Question 8

Function and full name of complex I?

Answer 8

NADH: ubuiquinone reductase or NADH dehydrogenase

Complex I transports electrons to co-enzyme Q (ubiquinone)

Translocates 4 H+ ions per NADH oxidised

Question 9

What electron transporting proteins are present in complex I? What else is present?

Answer 9

FeS (iron-sulphur centres)

FMN also present

all non-covalently bounds

Question 10

Most recent model of complex I?

Answer 10

Piston model