Oxidative phosphorylation

Where does oxidative phosphorylation take place?

Mitochondrial cristae

(inner mitochondrial membrane)

What is the 1st step?

The reduced NAD and FAD donate the electrons of the hydrogen atoms they are carrying to the first molecule in the electron transfer chain

(they’re oxidised by an electron carrier)

What happens as the electrons pass down the electron transfer chain?

The electrons pass along the electron transfer chain in a series of oxidation-reduction reactions

The energy they release causes the active transport of protons across the inner mitochondrial membrane and into the inter-membranal space

What happens once the protons are in the inter-membranal space?

They diffuse back into the mitochondrial matrix through ATP synthase channels

What happens at the end of the electron transfer chain?

The electrons combine with the protons and oxygen to form water

What does oxygen act as?

The final electron acceptor

What does the diagram look like for the chemiosmotic theory?

How do the electrons pass down the electron transfer chain?

They move down an energy gradient

This allows energy to be released gradually and more usefully

How are lipids used as respiratory substrates?

Lipids are first hydrolysed to glycerol and fatty acids

Glycerol is phosphorylated and converted to triose phosphate which enters the glycolysis pathway and then Krebs cycle

The fatty acid is broken down in to 2C fragments which are concerted to acetyl CoA which then enters the Krebs cycle

Why do lipids release more than double the energy of the same mass of carbohydrate?

The oxidation of lipids produced 2C fragments of carbohydrates and many hydrogen atoms

The hydrogen atoms are used to produce ATP during oxidative phosphorylation

How is protein used as a respiratory substance?

It is first hydrolysed to amino acids which have their amino groups removed (deamination)

3C compounds are converted to pyruvate

4C and 5C compounds are converted to intermediates in the Krebs cycle