9. 2 Polyisoprenoid biosynthesis 183 9. 3 Importance of cholesterol 184 9. 4 Further variations on the polyisoprenoid theme 199 9. 5 Biosynthesis of porphyrins 203 9. 6 Biosynthesis of chlorophyll 206 207 9. 7 Porphyrin degradation: bile pigment formation 9. 8 Vitamin B12 and pernicious anaemia 208 9. 9 Overview 209 Answers to exercises 210 Questions 211 Answers to questions 213 220 Glossary Index 222 Contents vii I / Editors' foreword This book is one of a series of brief fundamental texts for junior under­ graduates and diploma students in the biological sciences. The series, Molecular and Cell Biochemistry, covers the whole of modern biochemistry, integrating animal, plant and microbial topics. The intention is to give the series special appeal to the many students who read biochemistry for only part of their course and who are looking for an all-encompassing and stimulating approach. Although all books in the series bear a distinct family likeness, each stands on its own as an independent text. Many students, particularly those with less numerate backgrounds, find elements of their biochemistry courses daunting, and one of our principal concerns is to offer books which present the facts in a palatable style. Each chapter is prefaced by a list of learning objectives, with short summaries and revision aids at the ends of chapters.