CHAPTER 2 Single-Gene Inheritance

1. CHAPTER 2 • Single-Gene Inheritance

2. 2.2 Single-gene inheritance patterns • 2.3 The chromosomal basis of single-gene inheritance patterns • 2.1 Genes and chromosomes • 2.5 Sex-linked single-gene inheritance patterns • 2.6 Human pedigree analysis CHAPTER OUTLINE

3. Single-gene inheritance patterns

4. The monastery of the father of genetics, Gregor Mendel Chapter 2 Opener

5. The seven phenotypic pairs studied by Mendel Figure 2-9

6. Cross-pollination and selfing are two types of crosses Figure 2-10

7. Mendel’s crosses resulted in specific phenotypic ratios Figure 2-11

8. Table 2-1

9. A single-gene model explains Mendel’s ratios Figure 2-12

10. Mendel’s explanation: 1. Existence of genes – hereditary determinants of a particulate nature. 2. Genes are in pairs – alternative phenotypes of a character or trait are determined by different forms of a single type of gene – alleles. 3. Principle of segregation – members of the gene pair separate equally into gametes. 4. Gametic content – each gamete carries only one member of each gene pair. 5. Random fertilization – union of one gamete from each parent to form the offspring

11. Questions about heredity answered by Mendel: 1. What is inherited? alleles of genes 2. How are they inherited? according to principles of segregation and independent assortment 3. What is the role of chance? for each individual, inheritance is determined by chance, but within a population this chance operates in a context of strictly defined probabilities

12. The chromosomal basis of single-gene inheritance patterns

13. Stages of the asexual cell cycle Figure 2-13

14. Cell division in common life cycles Figure 2-14

15. Key stages of meiosis and mitosis Figure 2-15

16. Stages of Mitosis Box 2-1

17. Stages of Meiosis Box 2-2

18. Demonstration of equal segregation within one meiocyte in the yeast S. cerevisiae Figure 2-17

19. DNA molecules replicate to form identical chromatids Figure 2-18

20. Nuclear division at the DNA level Figure 2-19

21. Genes and chromosomes

22. The nuclear genome Figure 2-2

23. A diploid genome visualized Figure 2-3

24. Chromosomal DNA is wrapped around histones Figure 2-4a

25. Chromosomal DNA is wrapped around histones Figure 2-4b

26. Chromosomal condensation by supercoiling Figure 2-5

28. Progressive levels of chromosome packing 1. DNA winds onto nucleosome spools 2. The nucleosome chain coils into a solenoid 3. Solenoid forms loops, and the loops attach to a central scaffold 4. Scaffold plus loops arrange themselves into a giant supercoil

29. Visible chromosome landmarks

30. Chromosome number Highest known diploid chromosome number Indian fern Ophioglossum reticulatum (2n = 1260)

31. Chromosome size and type

34. Heterochromatin and euchromatin Feulgen stain Heterochromatin – densely staining region (more condensed) Euchromatin – poorly staining region (contains most of the active genes)

35. Centromeres Location of satellite DNA in mouse chromosomes

36. Telomeres

37. Banding patterns G-banding chromosomes of a human female (staining with Giemsa reagent)

38. Enlargement of chromosome 13

39. Labeling for G bands of chromosome 13

40. Landmarks that distinguish the chromosomes of corn Features such as size, arm ratio, heterochromatin, number and position of thickenings, number and location of nucleolar organizers, and banding pattern identify the individual chromosomes within the set that characterizes a species

41. Some landmarks of tomato chromosome 2 Figure 2-6

42. Representative chromosomal landscapes Figure 2-7

43. A specific human chromosomal landscape Figure 2-8

44. Sex-linked single-gene inheritance patterns

46. A dioecious plant species – Osmaronia dioica

47. A dioecious plant species – Aruncus diocius

48. Model Organism Drosophila Model Organism: Drosophila

49. Model Organism Drosophila Model Organism: Drosophila

50. Human sex chromosomes Figure 2-25