Lecture, three hours; discussion, one hour. Requisites: courses 30A, 30B, 30C, 153A. Covers fundamental chemical logic and enzyme mechanisms involved in biosynthesis of natural products. Discussion of major classes of natural product including polyketides, nonribosomal peptides, terpenes, alkaloids. Emphasis on biosynthetic logic used by nature to form complex molecules. Discussion of several important enzyme families in context of biosynthesis, including assembly-line megasynthases, group transferases, oxidoreductases, etc. Historical account of natural product isolation and characterization, as well as modern account of synthetic biology and genome based efforts that are used in discovery of new natural products. Includes extensive survey of scientific literature in format of presentations and discussions. Concurrently scheduled with course C238. Letter grading.