Genetics review Chapters 12-15

Mitosis Why mitosis? Homologous chromosomes Chromatids Haploid Diploid Binary fission Tumor Metastasis

Fig µmChromosomes Chromosome duplication (including DNA synthesis) Chromo- some arm Centromere Sister chromatids DNA molecules Separation of sister chromatids Centromere Sister chromatids

Fig S (DNA synthesis) MITOTIC (M) PHASE Mitosis Cytokinesis G1G1 G2G2

Fig b Cyclin is degraded Cdk MPF Cdk M S G1G1 G 2 checkpoint Degraded cyclin Cyclin (b) Molecular mechanisms that help regulate the cell cycle G2G2 Cyclin accumulation

Meiosis Genetic variation Chiasmata Synapsis

Mendel genetics Homozygous Heterozygous Parental, F 1, F 2 Genotype Phenotype Testcross Monohybrid Dihybrid

Mendel Law of segregation Law of independent assortment Incomplete dominance Codominance Multiple alleles Epistasis Pleiotropy Polygenes Dominant disorders

Fig

Fig P Generation Yellow-round seeds (YYRR) Y F 1 Generation Y R R R Y  r r r y y y Meiosis Fertilization Gametes Green-wrinkled seeds ( yyrr) All F 1 plants produce yellow-round seeds ( YyRr ) R R Y Y r r y y Meiosis R R Y Y r r y y Metaphase I Y Y RR r r y y Anaphase I r r y Y Metaphase II R Y R y y y y R R Y Y r r r r y Y Y R R yR Yr yr YR 1/41/4 1/41/4 1/41/4 1/41/4 F 2 Generation Gametes An F 1  F 1 cross-fertilization 9 : 3 : 1 LAW OF INDEPENDENT ASSORTMENT Alleles of genes on nonhomologous chromosomes assort independently during gamete formation. LAW OF SEGREGATION The two alleles for each gene separate during gamete formation

Wild type (w +)

Sex linked Hemophilia Color blindness Duchene’s muscular dystrophy

Fig P Generation F1F1 F2F2 All offspring had red eyes Sperm Eggs F1F1 F2F2 P Sperm Eggs   X X X Y CONCLUSION EXPERIMENT RESULTS w w w w w w w w w w ww w w w w w

Linked genes Genes on same chromosome Testcross more parental types

Fig Testcross parents Replication of chromo- somes Gray body, normal wings (F 1 dihybrid) Black body, vestigial wings (double mutant) Replication of chromo- somes b + vg + b vg b + vg + b + vg b vg + b vg Recombinant chromosomes Meiosis I and II Meiosis I Meiosis II b vg + b + vg b vg b + vg + Eggs Testcross offspring 965 Wild type (gray-normal) 944 Black- vestigial 206 Gray- vestigial 185 Black- normal b + vg + b vg b + vg b vg b vg + Sperm b vg Parental-type offspringRecombinant offspring Recombination frequency = 391 recombinants 2,300 total offspring  100 = 17%

Human disorders Aneuploidy Nondisjunction Down syndrome Klinefelter’s syndrome Turner syndrome Philadelphia chromosome Deletion, duplication, inversion, translation

Nondisjunction