Oxidative phosphorylation

Question 1

Explain the term ‘standard redox potential’

Answer 1

How readily X donates an electron compared to H2.

Question 2

What does it mean when X has a negative redox potential?

Answer 2

X has a lower affinity for electrons than H2. A positive H2 means the opposite.

Question 3

What is oxidative phosphorylation?

Describe the 2 stages.

Answer 3

The coupling of respiration to ATP synthesis.

1. Electrons move down the respiratory chain from NADH and FADH2 to O2. The energy realised is used to pump protons into the inter membrane space.
2. H+ move down there electrochemical gradient through ATP synthase to the mitochondrial matrix.

Question 4

Describe electron transport - respiratory chain

Answer 4

Four multisubunit complexes in inner mitochondrial membrane. Electrons are handed down from higher to lower redox potentials and eventually transfer to O2 to form H2O.

Question 5

What are cytochromes?

Answer 5

Cytochromes are proteins which contain a haem group as a co factor.

Fe(II) can take up and release electrons

Question 6

Name all the complexes in the respiratory chain. Look at diagram on page 11 of oxidative phosphorylation lecture.

Answer 6

1 NADH- Q oxidoreductase

2. Succinate- Q reductase
3. Q- Succinate c oxidoreductase
4. Cytochrome c oxidase

Question 7

Draw and label a diagram of ATP synthase

Answer 7

P15 of the oxidative phosphorylation lecture

Question 8

How much ATP does glucose yield

Answer 8

30-32 molecules

Question 9

What is the P/O ratio?

Answer 9

Number of Pi incorporated into ATP per Oxygen phosporylated. 2.5 for NADH and 1.5 for FADH2