Practice question

Genetic dissection models metabolism as ordered conversion chain where product of one enzymatic reaction becomes substrate for next ensuring directional flux toward final functional product. Enzymes act not randomly but in defined sequence establishing epistasis and accumulation patterns diagnostic for pathway order. B enzyme produces compound used by C enzyme so knockout of early enzyme prevents downstream synthesis of later intermediates. This sequential logic allows prediction of intermediate build-up and rescue patterns enabling mapping of steps to specific cistrons and understanding why upstream blocks have broader nutritional requirements than downstream blocks.