Question

Question #fc1c7

Answer 1

It grinds to a halt..

Explanation:

The final stage of cellular respiration is the electron transport chain. The electrons are passed via 3 large protein complexes (Complex I to Complex III), finally to arrive at Complex IV .

This enzyme, Cytochrome C Oxidase, or COX, finally passes the electrons over to Oxygen, forming `H_2O` in the process.

In the Active site are two haem-groups present (cytochromes `a` and `a_3`), along with two Copper centres (`Cu_a and Cu_b`). These centres are the docking sites for the Oxygen molecules.
Unfortunately, just like Carbon Monoxide, Cyanide has a stronger affinity for these centres than Oxygen does. and therefore binds competitively, and irreversibly, to the active `"Cytochrome " a_3-Cu_b` centre. It thereby prevents Oxygen molecules from docking, and the ETC grinds to a halt...