What are respiratory substrates? Name the most common respiratory substrate.

respiratory substrates are organic molecules oxidized during cellular respiration to release energy for ATP synthesis

• include carbohydrates (e.g., glucose), lipids (e.g., fatty acids), proteins (amino acids) and other compounds once preferred substrates are depleted

these substrates enter pathways such as glycolysis, β-oxidation and the citric acid cycle, generating reducing equivalents (NADH, FADH₂) for oxidative phosphorylation

the most common respiratory substrate is glucose, owing to its universal availability, ease of transport into cells and high ATP yield per unit oxygen consumed