Polyketide chain-extension framework: 1 acetyl (C2) + n malonyl (each adding C2) → C(2n+2) chain

Polyketide biosynthesis chain-extension arithmetic: each polyketide chain starts with an acetyl-CoA unit (C2) and is extended by n malonyl-CoA units. Each malonyl (C3) undergoes Claisen-type condensation with loss of CO₂, net-adding C2 to…