U3L3: Electron Transport Chain

Question 1

Where does the ETC occur and what way does it use to produce ATP?

Answer 1

inner mitochondrial membrane, uses oxidative phosphorylation

Question 2

Explain the process of the ETC

Answer 2

1) reduced NADH donates 2 electrons and 1 H+ ion to complex I (NADH gets oxidized as a result, and the NAD gets reused in AR)
2) reduced FADH2 donates 2 electrons and 2 H+ ions to complex II (FADH2 gets oxidized as a result, and the FAD gets reused in AR)
3) The electrons are passed by electron acceptors (cytochrome c and uq) in the electron transport chain (ETC), while the H+ ions stay in the matrix
4) As electrons move through the protein complexes, they go from higher to lower energy levels, releasing energy. This energy pumps hydrogen ions out of the matrix and into the intermembrane space, creating a H+ ion electrochemical gradient.
5) Electrons continue along the ETC until they reach the final electron acceptor – OXYGEN. Each oxygen atom combines with 2 electrons and 2 Hs to form 1 molecule of H2O.

Question 3

Explain the Chemiosmotic Synthesis of ATP

Answer 3

1) As the H+ ion concentration increases in the inter-membrane space, the electrical potential increases. The electrical potential energy is converted into chemical energy when they pass through ATP Synthase (last enzyme of the ETC)
2) The facilitated diffusion of H+ gives the chemical energy to ADP + Pi to create ATP. This is called chemiosmosis (aka oxidative phosphorylation)