Chemiosmosis

What does chemiosmosis require?

A membrane across which a gradient can be established - the inner mitochondrial membrane of the mitochondrion (proton and electrochemical gradients). Something which can use gradient energy to synthesise ATP

What can protons only diffuse down?

These 2 gradients through ATP synthases as the inner membrane is impermeable to protons

What spans the bilayer?

Protein channels for protons to diffuse down

What happens as protons pass through?

The energy they gain by being actively transported against their conc gradient is used to make ATP from ADP and Pi as the ATP synthases turn

What processes are similar in photosynthesis and respiration?

Photophosphorylation in photosynthesis and oxidative phosphorylation in respiration. Both use energy to pump protons across a membrane, building up a gradient for them. They diffuse down this gradient through ATPases producing ATP

What is evidence supporting chemiosmosis in terms of pH?

pH of the solution is a measure of proton concentration. In the mitochondria and chloroplasts the pH on one side of the membrane that contains ETC is higher than the other. This indicates protons are actively moved across the membrane

What do membranes in the mitochondria and chloroplasts do that supports chemisosmosis?

Make ATP even if there is no electron transport occurring providing there is a pH gradient across the membrane

What supports chemiosmosis in terms of chemicals?

Chemicals that prevent H ions being transported across the membrane can also stop ATP being produced

What supports chemiosmosis in terms of dinitrophenol?

It acts as a barrier for protons across membranes. If added to the thylakoid no proton gradient is built up. This is bcs as fast as membranes pump protons across them during electron transport, dinitrophenol allows ions to diffuse back down again. ETC happens as usual but no ATP is produced, showing that pH gradient is needed to make ATP