Question

In an electron transport chain, in terminal oxidation, the cytochrome which donates electrons to $O_2$ is

• A. Cytochrome b
• B. Cytochrome c
• C. Cytochrome $a_3$
• D. Cytochrome a

Answer 1

Answer: (C)

Cytochrome $a_3$

An electron transport chain is a series of compounds that transfer electrons from electron donors to electron acceptors via redox reactions and couples this electron transfer with the transfer of protons across a membrane. This creates an electrochemical proton gradient that drives ATP synthesis. Cytochrome $a_3$ is terminal cytochrome of ETC. It has $F{e}^{+++}$ and $C{u}^{++}$ both. With $F{e}^{+++}$, it picks up electrons and through $C{u}^{++}$ it passes electrons to oxygen.