Chemistry Labs

Biochemistry and biomedical chemistry

Metabolism (glycolysis, Krebs cycle, electron transport chain)

Metabolism is a network of linked reactions that captures energy and supplies building blocks; ATP and reduced cofactors connect pathways.

1 Lower secondary2 Upper secondary3 Undergraduate4 Advanced5 Research

IntuitionIntuition: the central idea

Metabolism is a network of linked reactions that captures energy and supplies building blocks; ATP and reduced cofactors connect pathways.

Explore the schematic model; it illustrates a concept rather than replacing experimental evidence.

SchoolSchool level: key concepts and a first application

Definition: Core concept

Glycolysis converts glucose to pyruvate in the cytosol, yielding net ATP and NADH. Aerobic oxidation then couples carbon oxidation to electron transport and ATP synthesis.

Glycolysis yields pyruvate, the pyruvate-dehydrogenase step produces acetyl-CoA, the TCA cycle regenerates oxaloacetate while reducing NAD⁺ and FAD, and the respiratory chain uses those reduced carriers.

Key terms and meaning
TermInterpretation
GlycolysisCytosolic pathway converting glucose to pyruvate with net ATP and NADH.
TCA cycleOxidizes acetyl-CoA, regenerates oxaloacetate and reduces cofactors.
Electron transportMembrane complexes transfer electrons from reduced cofactors to oxygen.

Example: Apply the idea

Why does inhibiting the mitochondrial electron-transport chain often reduce oxidative ATP synthesis?

Solution

Electron transfer normally pumps protons across the inner mitochondrial membrane. The resulting proton-motive force drives ATP synthase; blocking electron flow limits that gradient.

UndergraduateUniversity level: quantitative description

ΔG=ΔG∘′+RTln⁡Q\Delta G=\Delta G^{\circ\prime}+RT\ln Q

Under typical physiological conditions ATP hydrolysis is strongly favourable because QQ is far from equilibrium; pathway control depends on enzyme regulation, not only thermodynamics.

References