Oxidative phosphorylation

Question 1

Oxidative Phosphorylation

Answer 1

3 phenomena that result in the production of ATP. These 3 phenomena include:
a) The transfer of electrons from a reducing agent (usually NADH) along the electron transport chain

b) The pumping of protons out of the mitochondrial matrix by the electron transport chain complexes to form a proton gradient or proto-motive force
c) the utilisation of this proton gradient by ATP synthase to produce ATP. This ultimately results in the oxidation of molecular oxygen in the formation of H20.

Question 2

Site of oxidative phosphorylation

Answer 2

Mitochondria

Question 3

White muscle

Answer 3

Relies on anaerobic glycolysis for ATP requirements which facilitates rapid contraction but results in swift exhaustion (e.g. jaws of an alligator)

Question 4

Red muscle

Answer 4

Has numerous mitochondria, and relies on oxidative phosphorylation for ATP production which results in a sustained energy output

Question 5

What are the key features of mitochondrial structure which facilitate oxidative phosphorylation

Answer 5

a) the freely permeable outer mitochondrial membrane
b) an inter membrane space with similar ion/metabolite concentrations to the cytoplasm
c) An inner mitochondrial membrane virtually impermeable to polar or ionic substances (including protons)
d) The mitochondrial matrix which exhibits a high protein content due to the large number of enzymes present and hence a gel like consistency

Question 6

Chemiosmotic theory

Answer 6

Suggests that a proton gradient can serve as an energy reservoir for ATP synthesis or other energy requiring processes

Question 7

Role of molecular oxygen in electron transport chain

Answer 7

Molecular oxygen drives the electron transport chain by creating a difference in charges, driving the hydrogen/protons to travel towards the opposite charge which are accepted by oxygen and form water molecules. (note: oxygen splits in half to form water)

If a person is not breathing in enough molecular oxygen the electron transport chain stops working, ATP cant be produced and cells cannot carry out chemical reactions that require energy

Question 8

redox pair

Answer 8

the oxidised and reduced form of a molecule

Question 9

How does the proton pumping system of the electron transport chain work?

Answer 9

As electrons are passed between respiratory enzyme complexes, protons are initially accepted by the complex. As the electrons are passed to the next complex the accepted proton is released back to water. but on the other side of the complex which is exposed to the exterior of the mitochondrial inner membrane

Question 10

A low redox potential (-ve) suggests

Answer 10

strong donation of electrons

Question 11

A high redox potential (+ve) suggests

Answer 11

electrons will be freely accepted

Question 12

How are the components of the electron transport chain arranged and why? (i.e. regards to redox potential)

Answer 12

The components of the electron transport chain are arranged so that at the beginning of the chain there is a strong donator of electrons (NADH) and sequentially through the chain the redox potentials increase until the terminal electron acceptor (O2) is reached

Question 13

How much ATP can the ATP synthase complex produce per second?

Answer 13

up to 100 ATP per second

Question 14

Is the process of phosphorylation of ADP to form ATP reversible?

Answer 14

Yes

Question 15

Substrates needed for oxidative phosphorylation?

Answer 15

Pyruvate (for formation of NADH via the citric acid cycle), inorganic phosphate, ADP and the energy conserved in NADH molecules produced within the cytoplasm

Question 16

How do transporter proteins of pyruvate and Pi utilise the formation of a proton gradient to facilitate active transport ?

Answer 16

Utilise the favourable change in free energy associated with proton re-entry to the mitochondrial matrix to transport the substrate