Stoffwechselzwischenprodukte

Stoffwechsel, or metabolism, refers to the total of chemical reactions that sustain life in organisms. It encompasses catabolic pathways that break down nutrients to release energy and building blocks, and anabolic pathways that synthesize complex molecules from simpler ones. Metabolic reactions are organized into networks that transform energy, carbon, and electrons to support growth, maintenance, and reproduction. ATP and other energy carriers drive many steps, with specialized cofactors such as NADH and NADPH participating in redox reactions.

In cells, core metabolic pathways include glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation, which together extract energy from carbohydrates, fats, and proteins. Plants, algae, and some bacteria also use photosynthesis to capture light energy and fix carbon. Metabolic processes are compartmentalized in organelles in eukaryotes, notably mitochondria and, in plants, chloroplasts.

Regulation is achieved by enzymes, allosteric control, covalent modification, and hormonal signaling. Nutrient availability, energy status, and genetic factors shape metabolic rates, which can be assessed by basal metabolic rate and total energy expenditure. Disruptions in metabolism can lead to disorders such as diabetes, inherited metabolic diseases, or dyslipidemia, reflecting the importance of tightly controlled pathways.

Stoffwechsel is central to nutrition, medicine, and biotechnology, where understanding and redirecting metabolic flux enables health interventions, disease treatment, and industrial production of chemicals, fuels, and foods.