Mitochondria and oxidative phosphorylation

Question 1

Lable the diagram below add pic

Answer 1

add pic

Question 2

Oxidative phosphorylation proceeds in two steps: List these steps

Answer 2

1) The translocation or movement of protons from within the matrix of the mitachondria. This is controlled by the electron transport chain. The pumping of protons into the intermembrane space from the matrix establishes a gradient which can be looked at as a potential gradient or a pH gradient. 2)The pumped protons are allowed back into the mitachondria through a specific channel, which is coupled to an enzyme which can synthesise ATP (ATP synthase). The proton motive force that drives H+ back into the matrix space consists of a pH gradient AND a transmembrane electrical potential. add pic

Question 3

Name the enzymes and carries of the electron transport chain?

Answer 3

Membrane Complexes: NADH Dehydrogenase Complex Cytochrome b-c1 Complex Cytochrome Oxidase Complex

Mobile Carriers: Co-enzyme Q (ubiquinone) Cytochrome C add pic

Question 4

What two things can a ATP synthase enzyme do?

Answer 4

ATP synthesis ATP hydrolysis

Question 5

Why does FADH2 produce 2 ATP molecules?

Answer 5

Succinate Dehydrogenase is an integral membrane protein that is firmly attached to the inner surface of the inner mitochondrial membrane. This enzyme is responsible for catalysing the reaction which produces FADH2. It’s location allows it to communicate directly with ubiquinone hence FADH2 passes electrons directly to ubiquinone (co-enzyme Q) and fewer protons are pumped out so less ATP is produced. UBIQUINONE IS THE ENTRY POINT FOR ELECTRONS DONATED BY FADH2 add pic

Question 6

What is the final electron acceptor and what is the equation associated with this electron acceptor?

Answer 6

Oxygen add pic

Question 7

How does cyanide act as a poison?

Answer 7

binds to Fe3+ in haem group in cytochrome oxidase The binding of Cyanide to Cytochrome Oxidase blocks the flow of electrons though the respiratory chain and consequently, the production of ATP.

Question 8

How does Carbon Monoxide act as a poison?

Answer 8

Carbon Monoxide binds to the ferrous (Fe2+) form of the haem group, also blocking the flow of electrons. Cytochrome oxidase complex

Question 9

How does Malonate act as a poison?

Answer 9

competitive inhibitor to succinate dehydrogenase - slows down flow of electrons from succinate to ubiquinone

Question 10

How does Oligomycin act as a poison?

Answer 10

Oligomycin - binds to stalk of ATP synthase - blocks flow of protons through the enzyme

Question 11

How does Dinitrophenol act as a poison?

Answer 11

Induces weight loss by transporting protons across the mitochondrial membrane, thereby uncoupling oxidative phosphorylation from ATP production and therefore increasing metabolic rate and body temperature. Uncoupling = providing another path for the passage of a component of the ETC (in this case - protons)