oxidative phosphorylation

Question 1

processes involved in oxidative phosphorylation

Answer 1

1) the respiratory ETC, a series of enzyme complexes embedded in the inner mitochondrial membrane , oxidises NADH and FADH2 . electrons are passed from the reduced co-enzymes to O2. this process generates the proton gradient .

2) the proton concentration gradient is a reservoir of free energy - protons are channelled back across the inner membrane through an enzyme complex , atp synthase

Question 2

an endergonic reaction

Answer 2

a chemical reaction in which the standard change in free energy is positive and energy is absorbed

Question 3

chemiosmosis

Answer 3

the movement of ions across a semipermeable membrane down their electrochemical gradient.

Question 4

complex 1

Answer 4

the first complex NADH-co-Q oxidoreductase catalyses the transfer of electrons from NADH to co-enzyme Q
consists of at least 20 subunits , several proteins that contain iron-sulphur clusters and the flavoprotein that oxidises NADH.
the final electron receptor of complex 1, co-enzyme Q is mobile.
one of the 3 reactions responsible for proton pumping.

Question 5

complex 2

Answer 5

the second complex succinate-Co-Q oxidoreductase also catalyses the transfer of electrons to co-enzyme Co-Q.
substrate is succinate from the CAC , the product is fumarate and CoQH2

Question 6

complex 3

Answer 6

the third complex , CoQH2-cytochrome c oxidoreductase catalyses the oxidation of reduced co-enzyme Q (CoQH2)
when reduced CoQH2 is oxidised to CoQ the H+ passes out the other side of the membrane (2nd reaction)

Question 7

complex IV

Answer 7

the 4th complex , cytochrome C oxidase , catalyses the transfer of electrons from cytochrome C to oxygen
proton pumping also takes place

Question 8

Complex v

Answer 8

F0 sphere : spans the membrane and consists of 3 polypeptide chains and channels H+ through the inner membrane back into the matrix
F1 sphere : protects into the matrix and consists of 5 polypeptide chains and is the size of phosphorylation to ATP

Question 9

Summary of Oxidative Phosphorylation

Answer 9

Oxidative phosphorylation is themetabolic pathwayin whichcellsuseenzymestooxidizenutrients, thereby releasing energy which is used to reformATP. This takes place inside themitochondria.
During oxidative phosphorylation, electrons are transferred fromelectron donorstoelectron acceptorssuch asoxygen, inredox reactions. These redox reactions release energy, which is used to form ATP.
These redox reactions are carried out by a series ofprotein complexeswithin the inner membrane of the cell’s mitochondria. These linked sets of proteins are calledelectron transport chains. Five main protein complexes are involved, using a variety of electron donors and acceptors.
The energy released by electrons flowing through this electron transport chain is used to transportprotonsacross theinner mitochondrial membrane in a process calledelectron transport. This generatespotential energyin the form of apHgradient and anelectrical potentialacross this membrane. This store of energy is tapped by allowing protons to flow back across the membrane and down this gradient, through a large enzyme calledATP synthase; this process is known aschemiosmosis. This enzyme uses this energy to generate ATP fromadenosine diphosphate(ADP), in a phosphorylationreaction. This reaction is driven by the proton flow, which forces therotationof a part of the enzyme; the ATP synthase is a rotary mechanical motor.