1. Slide 1 Chapter 15: The Chromosomal Basis of Inheritance

2. Figure 15.1

3. Figure 15.2 P Generation F 1 Generation Yellow-round seeds (YYRR) Green-wrinkled seeds (yyrr)  Meiosis Fertilization Gametes Y Y R R Y R y y r y r All F 1 plants produce yellow-round seeds (YyRr). Meiosis Metaphase I Anaphase I Metaphase II R R R R R R R R R R R R rr r r rr r r r r r r YY Y Y Y Y Y Y Y Y Y Y y y y y y y y y y y y y Gametes LAW OF SEGREGATION The two alleles for each gene separate during gamete formation. LAW OF INDEPENDENT ASSORTMENT Alleles of genes on nonhomologous chromosomes assort independently during gamete formation. 12 21 1/41/4 1/41/4 1/41/4 1/41/4 YR yr Yr yR F 2 Generation 3 3 Fertilization recombines the R and r alleles at random. Fertilization results in the 9:3:3:1 phenotypic ratio in the F 2 generation. An F 1  F 1 cross-fertilization 9 : 3 : 1 r

4. Figure 15.3 Thomas Hunt Morgan and his Fruit Flies

5. Figure 15.4 All offspring had red eyes. P Generation F 1 Generation F 2 Generation F 1 Generation P Generation Eggs Sperm X X X Y ww ww ww ww ww ww ww ww ww ww ww w w w w ww RESULTS EXPERIMENT CONCLUSION Morgan’s Experiment

6. Figure 15.6 Parents or Sperm or Egg Zygotes (offspring) 44  XY 44  XX 22  X 22  Y 22  X 44  XX 44  XY 22  XX 22  X 76  ZW 76  ZZ 32 (Diploid) 16 (Haploid) (a) The X-Y system (b) The X-0 system (c) The Z-W system (d) The haplo-diploid system Sex Determination

7. Figure 15.5 X Y Human Sex Chromosomes

8. Figure 15.7 Eggs Sperm (a) (b) (c) XNXNXNXN XnYXnY XNXnXNXn XNYXNY XNXnXNXn XnYXnY XnXn Y XNXN Y Y XnXn XnXn XnXn XNXN XNXN XNXN XNXN XNXnXNXn XNYXNY XNYXNY XNYXNYXNYXNY XnYXnY XnYXnY XNXnXNXn XNXnXNXn XNXnXNXn XNXNXNXN XnXnXnXn Sex Linked Genes

9. Figure 15.8 Early embryo: X chromosomes Allele for orange fur Allele for black fur Two cell populations in adult cat: Cell division and X chromosome inactivation Active X Inactive X Active X Black fur Orange fur X Inactivation

10. Figure 15.9-1 P Generation (homozygous) Wild type (gray body, normal wings) b  b  vg  vg  b b vg vg Double mutant (black body, vestigial wings) EXPERIMENT

11. Figure 15.9-2 P Generation (homozygous) Wild type (gray body, normal wings) F 1 dihybrid (wild type) TESTCROSS b  b  vg  vg  b  b vg  vg b b vg vg Double mutant (black body, vestigial wings) Double mutant EXPERIMENT

12. Figure 15.9-3 P Generation (homozygous) Wild type (gray body, normal wings) F 1 dihybrid (wild type) Testcross offspring TESTCROSS b  b  vg  vg  b  b vg  vg b b vg vg Double mutant (black body, vestigial wings) Double mutant Eggs Sperm EXPERIMENT Wild type (gray-normal) Black- vestigial Gray- vestigial Black- normal b  vg  b vg b  vgb vg  b  b vg  vg b b vg vgb  b vg vgb b vg  vg b vg

13. Figure 15.9-4 P Generation (homozygous) Wild type (gray body, normal wings) F 1 dihybrid (wild type) Testcross offspring TESTCROSS b  b  vg  vg  b  b vg  vg b b vg vg Double mutant (black body, vestigial wings) Double mutant Eggs Sperm EXPERIMENT RESULTS PREDICTED RATIOS Wild type (gray-normal) Black- vestigial Gray- vestigial Black- normal b  vg  b vg b  vgb vg  b  b vg  vg b b vg vgb  b vg vgb b vg  vg 965 944 206 185 1 1 1 1 1 0 1 0 If genes are located on different chromosomes: If genes are located on the same chromosome and parental alleles are always inherited together: : : : : : : : : : b vg

14. Figure 15.UN01 Most offspring F 1 dihybrid female and homozygous recessive male in testcross or b + vg + b vg b + vg + b vg

15. Figure 15.UN02 Gametes from green- wrinkled homozygous recessive parent (yyrr) Gametes from yellow-round dihybrid parent (YyRr) Recombinant offspring Parental- type offspring YR yr Yr yR yr YyRr yyrr Yyrr yyRr

16. Figure 15.10 Testcross parents Replication of chromosomes Gray body, normal wings (F 1 dihybrid) Black body, vestigial wings (double mutant) Replication of chromosomes Meiosis I Meiosis II Meiosis I and II Recombinant chromosomes Eggs b  vg  b vg b  vg  b  vg b vg  b vg b  vg  b  vg b vg b vg  Testcross offspring 965 Wild type (gray-normal) 944 Black- vestigial 206 Gray- vestigial 185 Black- normal Sperm Parental-type offspring Recombinant offspring Recombination frequency 391 recombinants 2,300 total offspring  100  17%  b  vg  b vg  b  vg b vg

17. Figure 15.10a Testcross parents Replication of chromosomes Gray body, normal wings (F 1 dihybrid) Black body, vestigial wings (double mutant) Replication of chromosomes Meiosis I Meiosis II Meiosis I and II Recombinant chromosomes Eggs b  vg  b vg b  vg  b  vg b vg  b vg b  vg  b  vg b vg b vg  Sperm b vg

18. Figure 15.10b Testcross offspring 965 Wild type (gray-normal) 944 Black- vestigial 206 Gray- vestigial 185 Black- normal Sperm Parental-type offspringRecombinant offspring Recombination frequency 391 recombinants 2,300 total offspring  100  17%  b  vg  b vg  b  vg b vg Eggs Recombinant chromosomes b  vg  b vg b  vg b vg 

19. Figure 15.11 Chromosome Recombination frequencies 9% 9.5% 17% b cn vg RESULTS

20. Figure 15.12 Mutant phenotypes Short aristae Black body Cinnabar eyes Vestigial wings Brown eyes Long aristae (appendages on head) Gray body Red eyes Normal wings Red eyes Wild-type phenotypes 104.5 67.057.5 48.5 0

21. Slide 21 Chromosomal Mutations Alteration of chromosome numberAlteration of chromosome number AneuploidyAneuploidy Monosomic (2n – 1)Monosomic (2n – 1) Trisomic (2n + 1)Trisomic (2n + 1) PolyploidyPolyploidy Alteration in chromosome structureAlteration in chromosome structure

22. Slide 22 Chromosomal Mutations Alteration of chromosome numberAlteration of chromosome number AneuploidyAneuploidy Monosomic (2n – 1)Monosomic (2n – 1) Trisomic (2n + 1)Trisomic (2n + 1) PolyploidyPolyploidy Alteration in chromosome structureAlteration in chromosome structure

23. Figure 15.13-3 Meiosis I Meiosis II Nondisjunction Non- disjunction Gametes Number of chromosomes Nondisjunction of homo- logous chromosomes in meiosis I (a) Nondisjunction of sister chromatids in meiosis II (b) n  1 n  1 n  1 n  1 n  1 n n

24. Figure 15.15

25. Slide 25 Aneuploidy in Sex Chromosomes

26. Slide 26 Chromosomal Mutations Alteration of chromosome numberAlteration of chromosome number AneuploidyAneuploidy Monosomic (2n – 1)Monosomic (2n – 1) Trisomic (2n + 1)Trisomic (2n + 1) PolyploidyPolyploidy Alteration in chromosome structureAlteration in chromosome structure

27. Slide 27 Chromosomal Mutations Alteration of chromosome numberAlteration of chromosome number AneuploidyAneuploidy Monosomic (2n – 1)Monosomic (2n – 1) Trisomic (2n + 1)Trisomic (2n + 1) PolyploidyPolyploidy Alteration in chromosome structureAlteration in chromosome structure

28. Figure 15.14 (a) Deletion (b) Duplication (c) Inversion (d) Translocation A deletion removes a chromosomal segment. A duplication repeats a segment. An inversion reverses a segment within a chromosome. A translocation moves a segment from one chromosome to a nonhomologous chromosome. ABCDEFGH ABCEFGH ABCDEFGH ABCDEFGHBC ABCDEFGH ADCBEFGH ABCDEFGH MNOPQR G MNOC HFED ABPQ R

29. Figure 15.16 Normal chromosome 9 Normal chromosome 22 Reciprocal translocation Translocated chromosome 9 Translocated chromosome 22 (Philadelphia chromosome)

30. Slide 30 Exceptions to Chromosome Theory Genomic imprintingGenomic imprinting Organelle genesOrganelle genes