Gene action in pathways

(a) In anabolic pathways the sequential action of gene products catalyzes steps of a biosynthesis. Gene Met 2 Met 8 Met C Met E Homoserine Cystothionine Cystothionine Homocysteine Enzyme product transacetylase gamma synthetase beta Iyase methyltransferase Pathway compound Homoserine J—e Cysteine J—e Cystathionine .L. Homocysteine L Methionine (b) The action of gene products in catabolic pathways breaks down complex compounds into simpler compounds. f_fl L Dietary protein Phenylalanine Tyrosinemia hydroxylase aminotransferase l l Phenylalanine +Tyrosine +> p-Hydroxyphenylalanine (PHPA) Phenylketonuria Tyrosinemia type II (OMIM 261600) (OMIM 276600) Tyrosinase —> PHPA dioxygenase —> Albinism Tyrosinemia type III (OMIM 203100) (OMIM 276710) Melanins Homogentisic acid (HGA) HGA oxidase —> Alkaptonuria (OMIM 203500) Malevlacetoacetic acid