Preface vi 



PART 1 ORGANISMS: 

 ORIGIN AND FUNCTION 



Chapter 1 ] The Origin of Life 



The Early Stages 6 

 Origin of Self-replicating Systems 

 Energy Sources 9 

 Origin of Structure 12 

 Origin of the Genetic Code 13 

 Reading the Code 17 

 Summary 19 

 References 21 



Chapter 2 ! Units of Replication 22 



Structure of Cells 23 

 Cell Division: Mitosis 27 

 Cell Division: Meiosis 31 

 Summary 35 

 References 35 



Chapter 3 Genetics 36 



Variation and Mendelian Genetics 37 



The Units of Heredity 38 



Mendel's Laws 39 



Recombination 40 



The Expression of Genes 42 



Mutation 44 



Evolution of Dominance 45 



Chromosomal Mechanisms 46 



Sex Chromosomes 47 



Alterations of the Chromosomes 48 

 Deletions and Duplications 48 

 Inversions and Translocations 49 '^ 



