Which of the following is a prosthetic group present in several components of the electron transport chain?

• A. Biotin
• B. Thiamine pyrophosphate
• C. Heme
• D. Cobalamin

Answer: (C)

Verified step by step guidance

1. Understand the concept of a prosthetic group: A prosthetic group is a non-protein molecule that is tightly bound to a protein and is essential for its biological activity. In the context of the electron transport chain, prosthetic groups play a critical role in facilitating electron transfer.
2. Review the components of the electron transport chain: The electron transport chain consists of protein complexes and molecules such as cytochromes, which contain prosthetic groups like heme. Heme is a key prosthetic group that helps in electron transfer by cycling between reduced and oxidized states.
3. Analyze the options provided: Biotin, Thiamine pyrophosphate, and Cobalamin are cofactors involved in other biochemical processes, but they are not prosthetic groups in the electron transport chain. Heme, on the other hand, is specifically associated with cytochromes in the electron transport chain.
4. Relate heme to its function: Heme contains an iron atom that can accept and donate electrons, making it crucial for the redox reactions in the electron transport chain. This property allows it to facilitate the transfer of electrons between complexes.
5. Conclude the reasoning: Based on the information above, the correct answer is Heme, as it is the prosthetic group present in several components of the electron transport chain, specifically in cytochromes.