CHAPTER 4 THE CHROMOSOMAL BASIS OF MENDEL'S PRINCIPLES OF SEGREGATION AND INDEPENDENT ASSORTMENT 95 SOLVE IT Sex Chromosome Nondisjunction 95 Extensions of Mendelism 62 PROBLEM-SOLVING SKILLS Tracking X-Linked Genetics Grows Beyond Mendel's Monastery and Autosomal Inheritance 97 Garden 62 Sex-Linked Genes in Humans 98 Allelic Variation and Gene Function 63 HEMOPHILIA,AN X-LINKED BLOOD-CLOTTING DISORDER 98 INCOMPLETE DOMINANCE AND CODOMINANCE 63 COLOR BLINDNESS,AN X-LINKED VISION DISORDER 98 MULTIPLE ALLELES 64 GENES ON THE HUMAN Y CHROMOSOME 100 ALLELIC SERIES 65 SOLVE IT Calculating the Risk for Hemophilia 100 TESTING GENE MUTATIONS FOR ALLELISM 65 GENES ON BOTH THE X AND Y CHROMOSOMES 100 SOLVE IT The Test for Allelism 66 VARIATION AMONG THE EFFECTS OF MUTATIONS 66 Sex Chromosomes and Sex GENES FUNCTION TO PRODUCE POLYPEPTIDES 67 Determination 100 FOCUS ON Genetic Symbols 68 SEX DETERMINATION IN HUMANS 101 WHY ARE SOME MUTATIONS DOMINANT AND OTHERS SEX DETERMINATION IN DROSOPHILA 102 RECESSIVE?68 SEX DETERMINATION IN OTHER ANIMALS 102 Gene Action:From Genotype to Phenotype 70 Dosage Compensation of X-Linked INFLUENCE OF THE ENVIRONMENT 70 Genes 104 ENVIRONMENTAL EFFECTS ON THE EXPRESSION OF HUMAN HYPERACTIVATION OF X-LINKED GENES IN MALE GENES 70 DROSOPHILA 104 PENETRANCE AND EXPRESSIVITY 71 INACTIVATION OF X-LINKED GENES IN FEMALE MAMMALS 104 GENE INTERACTIONS 72 EPISTASIS 72 PLEIOTROPY 75 PROBLEM-SOLVING SKILLS Going from Pathways CHAPTER 6 to Phenotypic Ratios 76 Inbreeding:Another Look at Pedigrees 77 Variation in Chromosome THE EFFECTS OF INBREEDING 77 Number and Structure 110 GENETIC ANALYSIS OF INBREEDING 78 Chromosomes,Agriculture,and Civilization 110 SOLVE IT Compound Inbreeding 81 MEASURING GENETIC RELATIONSHIPS 82 Cytological Techniques 111 ANALYSIS OF MITOTIC CHROMOSOMES 111 THE HUMAN KARYOTYPE 113 CYTOGENETIC VARIATION:AN OVERVIEW 114 CHAPTER 5 Polyploidy 115 STERILE POLYPLOIDS 115 The Chromosomal Basis of FERTILE POLYPLOIDS 116 Mendelism 89 SOLVE IT Chromosome Pairing in Polyploids 117 Sex,Chromosomes,and Genes 89 TISSUE-SPECIFIC POLYPLOIDY AND POLYTENY 117 Chromosomes 90 Aneuploidy 119 CHROMOSOME NUMBER 90 TRISOMY IN HUMANS 120 SEX CHROMOSOMES 90 MONOSOMY 121 The Chromosome Theory of Heredity 92 FOCUS ON Amniocentesis and Chorionic Biopsy 123 EXPERIMENTAL EVIDENCE LINKING THE INHERITANCE OF PROBLEM-SOLVING SKILLS Tracing Sex GENES TO CHROMOSOMES 92 Chromosome Nondisjunction 124 NONDISJUNCTION AS PROOF OF THE CHROMOSOME DELETIONS AND DUPLICATIONS OF CHROMOSOME THEORY 93 SEGMENTS 124x CHAPTER 4 Extensions of Mendelism 62 Genetics Grows Beyond Mendel’s Monastery Garden 62 Allelic Variation and Gene Function 63 INCOMPLETE DOMINANCE AND CODOMINANCE 63 MULTIPLE ALLELES 64 ALLELIC SERIES 65 TESTING GENE MUTATIONS FOR ALLELISM 65 SOLVE IT The Test for Allelism 66 VARIATION AMONG THE EFFECTS OF MUTATIONS 66 GENES FUNCTION TO PRODUCE POLYPEPTIDES 67 FOCUS ON Genetic Symbols 68 WHY ARE SOME MUTATIONS DOMINANT AND OTHERS RECESSIVE? 68 Gene Action: From Genotype to Phenotype 70 INFLUENCE OF THE ENVIRONMENT 70 ENVIRONMENTAL EFFECTS ON THE EXPRESSION OF HUMAN GENES 70 PENETRANCE AND EXPRESSIVITY 71 GENE INTERACTIONS 72 EPISTASIS 72 PLEIOTROPY 75 PROBLEM-SOLVING SKILLS Going from Pathways to Phenotypic Ratios 76 Inbreeding: Another Look at Pedigrees 77 THE EFFECTS OF INBREEDING 77 GENETIC ANALYSIS OF INBREEDING 78 SOLVE IT Compound Inbreeding 81 MEASURING GENETIC RELATIONSHIPS 82 CHAPTER 5 The Chromosomal Basis of Mendelism 89 Sex, Chromosomes, and Genes 89 Chromosomes 90 CHROMOSOME NUMBER 90 SEX CHROMOSOMES 90 The Chromosome Theory of Heredity 92 EXPERIMENTAL EVIDENCE LINKING THE INHERITANCE OF GENES TO CHROMOSOMES 92 NONDISJUNCTION AS PROOF OF THE CHROMOSOME THEORY 93 THE CHROMOSOMAL BASIS OF MENDEL’S PRINCIPLES OF SEGREGATION AND INDEPENDENT ASSORTMENT 95 SOLVE IT Sex Chromosome Nondisjunction 95 PROBLEM-SOLVING SKILLS Tracking X-Linked and Autosomal Inheritance 97 Sex-Linked Genes in Humans 98 HEMOPHILIA, AN X-LINKED BLOOD-CLOTTING DISORDER 98 COLOR BLINDNESS, AN X-LINKED VISION DISORDER 98 GENES ON THE HUMAN Y CHROMOSOME 100 SOLVE IT Calculating the Risk for Hemophilia 100 GENES ON BOTH THE X AND Y CHROMOSOMES 100 Sex Chromosomes and Sex Determination 100 SEX DETERMINATION IN HUMANS 101 SEX DETERMINATION IN DROSOPHILA 102 SEX DETERMINATION IN OTHER ANIMALS 102 Dosage Compensation of X-Linked Genes 104 HYPERACTIVATION OF X-LINKED GENES IN MALE DROSOPHILA 104 INACTIVATION OF X-LINKED GENES IN FEMALE MAMMALS 104 CHAPTER 6 Variation in Chromosome Number and Structure 110 Chromosomes, Agriculture, and Civilization 110 Cytological Techniques 111 ANALYSIS OF MITOTIC CHROMOSOMES 111 THE HUMAN KARYOTYPE 113 CYTOGENETIC VARIATION: AN OVERVIEW 114 Polyploidy 115 STERILE POLYPLOIDS 115 FERTILE POLYPLOIDS 116 SOLVE IT Chromosome Pairing in Polyploids 117 TISSUE-SPECIFIC POLYPLOIDY AND POLYTENY 117 Aneuploidy 119 TRISOMY IN HUMANS 120 MONOSOMY 121 FOCUS ON Amniocentesis and Chorionic Biopsy 123 PROBLEM-SOLVING SKILLS Tracing Sex Chromosome Nondisjunction 124 DELETIONS AND DUPLICATIONS OF CHROMOSOME SEGMENTS 124