Question

The terminal cytochrome of the respiratory chain which donates electrons to oxygen is

• A. Cyt C
• B. Cyt b
• C. Cyt a3
• D. Cyt a

Answer 1

The correct option is C

Cyt a3

The correct option is C

Explanation of the correct option:

1. As a component of complex IV, cytochrome a3 is a cytochrome c oxidase that transports electrons to oxygen.
2. ATP synthase produces ATP in tandem with the transfer of electrons in the electron transport chain.
3. A series of substances that undergo redox reactions in a chain of electron transport. It combines this electron transport over a membrane with proton transfer and occurs from electron donors to electron acceptors. As a result, an electrochemical protons gradient is created, driving ATP production.
4. Cytochrome a3 is the final cytochrome of ETC. Both Fe3+ and Cu2+ are present. It takes up electrons using Fe3+ and uses Cu2+ to transport them to oxygen.

Explanation of the incorrect option:

Option A:

1. In the mitochondrial electron transport chain, cytochrome C serves a functional purpose.
2. The process for ATP production includes that electron transport.
3. Cytochrome C is responsible for transporting electrons across the inner mitochondrial membrane's complex of integral membrane proteins.

Option B:

1. Cytochrome B is a part of respiratory chain complex III, commonly referred to as the bc1 complex or ubiquinol-cytochrome c reductase, which is found in the mitochondria of aerobic prokaryotes and eukaryotes.
2. Cytochrome B6, a subunit of the plastoquinone-plastocyanin reductase, sometimes referred to as the b6f complex, is a related protein found in cyanobacteria and plant chloroplasts.
3. These complexes are engaged in proton pumping to produce a proton-motive force, as well as electron transport (PMF). To produce ATP, this proton gradient is employed.

Option D:

1. They carry out redox reactions in the cells and aid in electron transport in the mitochondrial electron transport system.
2. They are also known as "haem-proteins" due to the presence of the heme group.

Final answer: The terminal cytochrome of the respiratory chain which donates electrons to oxygen is Cyt a3.