Learn / Metabolism

Metabolic pathways

Every FMK pathway as a clickable map. Pick one pathway to hammer it — next step, enzyme, regulator, cofactor, and the facts that get tested (NADPH and who needs it, rate-limiting steps, deficiencies) — or set it to all pathways for a mixed drill. Every answer says which enzyme and which pathway.

Pathway

Fructose metabolism · Liver (90% first-pass); minor in muscle/adipose via hexokinase. Enzymes sit beside the arrows; a ★ marks the rate-limiting step. The map scrolls inside its panel.

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Fructose metabolism

Fructose-1-phosphate

Made from Fructose by Fructokinase

Fructokinase · irreversible — Fructose metabolism

Cofactors: ATP → ADP

Deficiency: Essential fructosuria — benign; fructose in blood/urine (positive copper-reduction test, negative glucose oxidase); no treatment

Liver, kidney, intestine. High Vmax — fructose is grabbed fast, consuming ATP.

Condition cards:Essential fructosuria →

Becomes DHAP via Aldolase B ★

Aldolase B ★ rate-limiting — Fructose metabolism

Deficiency: Hereditary fructose intolerance — F1P accumulates, traps Pi → ↓ATP → gluconeogenesis and glycogenolysis fail: vomiting, hypoglycemia, jaundice, hepatomegaly after fruit/sucrose; avoid fructose, sucrose AND sorbitol

The regulated step of hepatic fructose handling.

Condition cards:Hereditary fructose intolerance (secondary hyperuricemia) →

Becomes Glyceraldehyde via Aldolase B

Aldolase B — Fructose metabolism

Condition cards:Hereditary fructose intolerance (secondary hyperuricemia) →