Since no molecular oxygen participates in the citric acid cycle, the steps in which acetyl groups are oxidized to CO₂ involve removal of hydride ions and hydrogen ions. What is the acceptor of hydride ions? What is the acceptor of hydrogen ions?

Verified step by step guidance

1. Identify the role of the citric acid cycle in cellular respiration, which involves the oxidation of acetyl groups to CO₂.
2. Understand that during the oxidation process, electrons are removed in the form of hydride ions (H⁻) and hydrogen ions (H⁺).
3. Recognize that the hydride ions (H⁻) are typically accepted by NAD⁺, converting it to NADH.
4. Note that FAD can also act as an acceptor of electrons, accepting two hydrogen atoms to form FADH₂.
5. Understand that the hydrogen ions (H⁺) are released into the mitochondrial matrix, contributing to the proton gradient used in ATP synthesis.

Key Concepts

Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle, is a series of enzymatic reactions that occur in the mitochondria, where acetyl-CoA is oxidized to produce energy. This cycle is crucial for cellular respiration, as it generates electron carriers like NADH and FADH₂, which are essential for the electron transport chain. Importantly, molecular oxygen is not directly involved in the cycle, but it is necessary for the subsequent oxidative phosphorylation process.

Hydride Ion Transfer

In biochemical reactions, hydride ions (H⁻) are often transferred from substrates to electron acceptors, playing a key role in oxidation-reduction reactions. In the citric acid cycle, NAD⁺ serves as the primary acceptor of hydride ions, converting to NADH. This transfer is vital for energy production, as NADH later donates electrons to the electron transport chain, ultimately leading to ATP synthesis.

Proton Transfer

Proton transfer refers to the movement of hydrogen ions (H⁺) during biochemical reactions, which can influence pH and energy dynamics within cells. In the context of the citric acid cycle, FAD is the main acceptor of hydrogen ions, becoming FADH₂. This process is essential for maintaining the balance of redox reactions and contributes to the overall energy yield from the oxidation of acetyl groups.