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.
Purine synthesis & salvage
dADP / dGDP (dNDP)
Made from ADP / GDP (NDP) by Ribonucleotide reductase (RNR)
Ribonucleotide reductase (RNR) · irreversible — Purine synthesis & salvage
Cofactors: Thioredoxin (re-reduced by thioredoxin reductase, NADPH)
Activated by: ATP
Inhibited by: dATP (allosteric — the ADA-deficiency mechanism); Hydroxyurea
The ONLY route from ribonucleotides to deoxyribonucleotides; up-regulated in S phase. Hydroxyurea blocks it (antineoplastic; low-dose in sickle cell to raise HbF).
Condition cards:Hydroxyurea →