Question

In otherwise normal, intact (not leaky), coupled mitochondria supplied with succinate and ADP, if you add the uncoupler CCCP:

a. What happens to electron- transport (works/stops)? Why?

b. What happens to oxygen consumption (works/stops)? Why?

c. What happens to proton pumping (works/stops)? Why?

d. What happens to ATP synthesis (works/stops)? Why?

Answer 1

Answer :

Carbonyl Cyanide m-chlorophenyl hydrazone (CCCP) causes slow and gradual cell death through many different ways. It is a chemical inhibitor of oxidative phosphorylation. It affects Protein synthesis, proton gradient, Electron transport chain (ETC) and ATP Synthase.

a. Electron Transport chain stops across the membrane because it gets decoupled from protons. As there are no acceptors for the electrons, the chain becomes inhibited and stops its work.

b. Oxygen consumption initially increases tremendously because the mitochondria tries to compensate for stoppage of ETC by getting more Oxygen.

c. CCCP causes uncoupling of proton gradient that was otherwise established while normal running of the ETC. CCCP transports protons across the inner mitochondrial membrane disrupting the proton pump indirectly.

d. The ATP synthesis is reduced and eventually stopped by CCCP. It acts as an Ionophore and reduces the ability of enzyme ATP synthase which is responsible for ATP synthesis. Coupled with ETC and proton pump disruptions, ATP synthesis reduces considerably until it comes to a standstill.