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
Cholesterol synthesis · Cytosol / smooth ER — mainly liver. Enzymes sit beside the arrows; a ★ marks the rate-limiting step. The map scrolls inside its panel.
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Acetyl-CoA (cytosol)Acetyl-CoA (cytosol)Acetoacetyl-CoAAcetoacetyl-CoAHMG-CoA (cytosolic)HMG-CoA (cytosolic)MevalonateMevalonateIsoprenoid units (IPP)Isoprenoid units (IPP)Squalene (C30)Squalene (C30)LanosterolLanosterolCholesterol (C27)Cholesterol (C27)Bile acidsBile acidsVitamin DVitamin DSteroid hormonesSteroid hormonesThiolaseHMG-CoA synthase (cytosolic)HMG-CoA reductase ★Mevalonate kinases / decarboxylasePrenyl transferases → squalenesynthaseSqualene epoxidase → cyclase~19 steps (loses 3 methyl groups)Cholesterol 7α-hydroxylase(CYP7A1, rate-limiting)7-Dehydrocholesterol → UV-B (skin)→ 25-OH (liver) → 1,25-(OH)₂(kidney, 1α-hydroxylase)Desmolase / CYP450 side-chaincleavage (adrenal, gonads)

Cholesterol synthesis

Steroid hormones

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