Question

In the electron transport chain, flavin mononucleotide (FMN) can adopt___ as the highest oxidation state and is capable of accepting or donating___. electrons, respectively.

• A. 2; 2 or 3
• B. 2; 1 or 2
• C. 3; 2 or 3
• D. 3; 1 or 2

Answer 1

The Correct Option is D

The problem discusses the role of flavin mononucleotide (FMN) within the electron transport chain, specifically regarding its oxidation state capabilities and electron transfer potential.

Let's break down each part of the question:

• **Highest Oxidation State of FMN:**
  • FMN, a derivative of riboflavin, is capable of participating in redox reactions within biological systems.
  • It acts as an electron carrier by cycling between different oxidation states.
  • The highest oxidation state that flavin mononucleotide can achieve is +3, which reflects that it has released electrons leading to a more oxidized state.
• **Number of Electrons FMN Can Accept or Donate:**
  • FMN can cycle between FMN, FMNH_• (semiquinone form), and FMNH₂ (fully reduced form).
  • This means FMN can accept or donate 1 electron to form the semiquinone radical or 2 electrons to form FMNH₂.
  • Therefore, the number of electrons FMN is capable of accepting or donating is 1 or 2, depending on the redox reaction occurring.

After analyzing the statements, the answer is better understood:

Option	Explanation
2; 2 or 3	FMN has a maximum oxidation state of +3, not 2, which makes this option incorrect.
2; 1 or 2	The maximum oxidation state is incorrect; it should be +3.
3; 2 or 3	FMN can accept/donate 1 or 2 electrons, not 2 or 3. This option is incorrect.
3; 1 or 2	This option correctly identifies FMN's highest oxidation state and the number of electrons it can exchange.

Therefore, the correct option is 3; 1 or 2. This answer selection is aligned with the electron transfer capabilities and oxidation states of FMN in biological redox systems like the electron transport chain.