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

Fatty acid synthesis · Cytosol — liver, adipose, lactating mammary gland (fed state, insulin). Enzymes sit beside the arrows, ★ = rate-limiting, ⊕/⊖ = activators/inhibitors (toggle), −ATP +NADH = what the step spends and makes (toggle ⚡), dashed = allosteric signal, shaded bands = compartment. Drag to pan.

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Fatty acid synthesis

Palmitate (C16)

Made from Malonyl-CoA by Fatty acid synthase (FAS)

Fatty acid synthase (FAS) — Fatty acid synthesis

Cofactors: 2 NADPH per 2-carbon addition, Pantothenate (ACP arm, B₅)

7 malonyl-CoA + 1 acetyl-CoA + 14 NADPH → palmitate (C16). Elongation/desaturation in the ER afterwards. NADPH comes from the HMP shunt and malic enzyme.

Made from NADPH (HMP shunt, malic enzyme) by NADPH supply (2 per elongation)

NADPH supply (2 per elongation) — Fatty acid synthesis

Why the HMP shunt is most active in lipogenic tissues.

Becomes Triacylglycerol → VLDL via Acyltransferases (glycerol-3-P backbone)

Acyltransferases (glycerol-3-P backbone) — Fatty acid synthesis

Esterified to TG in the liver and exported as VLDL; in adipose stored in the droplet.