Fadh2
Fadh2 - Related Videos
01:31
ATP Yield
0 Views •
2019
Cellular respiration produces 30 - 32 ATP per glucose molecule. Although most of the ATP results from oxidative phosphorylation and the electron transport chain (ETC), 4 ATP are gained beforehand (2 from glycolysis and 2 from the citric acid cycle). The ETC is embedded in the inner mitochondrial membrane and is comprised of four main protein complexes and an ATP synthase. NADH and FADH2 pass electrons to these complexes, which pump protons into the intermembrane space. This distribution of...
01:28
Electron Transport Chains
0 Views •
2019
The final stage of cellular respiration is oxidative phosphorylation that consists of two steps: the electron transport chain and chemiosmosis. The electron transport chain is a set of proteins found in the inner mitochondrial membrane in eukaryotic cells. Its primary function is to establish a proton gradient that can be used during chemiosmosis to produce ATP and generate electron carriers, such as NAD+ and FAD, that are used in glycolysis and the citric acid cycle. The ETC is comprised of...
02:36
The Citric Acid Cycle
0 Views •
2019
The citric acid cycle, also known as the Krebs cycle or TCA cycle, consists of several energy-generating reactions that yield one ATP molecule, three NADH molecules, one FADH2 molecule, and two CO2 molecules. Acetyl CoA is the point-of-entry into the citric acid cycle, which occurs in the inner membrane (i.e., matrix) of mitochondria in eukaryotic cells or the cytoplasm of prokaryotic cells. Prior to the citric acid cycle, pyruvate oxidation produced two acetyl CoA molecules per glucose...
08:32
The ATP Bioluminescence Assay
0 Views •
2023
In fireflies, the luciferase enzyme converts a compound called luciferin into oxyluciferin, and produces light or “luminescence” as a result. This reaction requires energy derived from ATP in order to proceed, so researchers have exploited the luciferase-luciferin interaction to gauge ATP levels in cells. Given ATP’s role as the cell’s currency of energy, the ATP bioluminescence assay can provide insight into cellular metabolism and overall cell health.In this video, JoVE discusses cellular...
FAQs
The difference comes from where their electrons enter the respiratory chain. FADH2 transfers electrons to ubiquinone through Complex II, so it bypasses Complex I. Because its electrons enter downstream, they contribute less to proton-gradient formation and consequently drive less ATP synthesis during oxidative phosphorylation. This distinction explains why electron carriers do not produce identical ATP yields.
Succinate dehydrogenase couples the oxidation of succinate to the reduction of FAD. As succinate becomes fumarate, FAD accepts two electrons and two hydrogen ions, forming FADH2. The enzyme therefore links a citric acid cycle reaction with electron delivery to the respiratory chain, allowing reducing power from nutrient oxidation to enter aerobic respiration through Complex II.
Ubiquinone receives the electrons transferred from FADH2 through respiratory Complex II. This makes it a connection between the flavin-containing reaction and later stages of the mitochondrial electron transport chain. Because the electrons reach ubiquinone rather than entering through Complex I, their movement supports proton-gradient formation indirectly and produces a lower ATP yield than NADH oxidation.
FADH2 also participates in fatty-acid oxidation and related metabolic pathways, extending its role beyond the succinate-to-fumarate reaction. In these settings, it carries reducing power generated during nutrient oxidation toward the respiratory machinery. Including these pathways gives a broader biological view of how cells channel energy from different nutrient sources into aerobic respiration.
Its formation marks the capture of electrons and hydrogen ions released during oxidation reactions. Subsequent transfer through Complex II and ubiquinone connects that captured reducing power with respiratory-chain activity. Studying this sequence helps clarify how chemical energy in nutrients becomes a proton gradient and is ultimately converted into ATP during oxidative phosphorylation.
Electron transfer from FADH2 contributes indirectly to formation of the mitochondrial proton gradient. That gradient provides the driving force for ATP synthesis during oxidative phosphorylation. Since these electrons enter downstream of Complex I, the resulting contribution is smaller than that associated with NADH, making FADH2 an important factor when comparing energy yields from respiratory pathways.