- Gregor Mendel, an Augustinian monk in the late 1800s, is considered the founder of genetics for his experiments breeding pea plants. He studied traits like flower color, seed texture, and pod shape. - Mendel discovered that traits are passed from parents to offspring through discrete units called genes, located on chromosomes. Genes come in different forms called alleles that give rise to different traits. - Through experiments breeding thousands of pea plants, Mendel determined that alleles segregate and assort independently during reproduction according to his laws of inheritance. This laid the foundation for modern genetics.

1. Patterns of Inheritance

7. Genes, Alleles, Loci, and Chromosomes Chromosome from One Parent Homologous Chromosome from Other Parent M locus has gene that controls leaf color . Plant homozygous for this gene D locus has gene that controls plant height . Plant homozygous for this gene Bk locus has gene that controls fruit shape . Plant heterozygous for this gene 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Loci: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Loci:

9. Seeds & Flowers of Edible Pea Intact pea flower Flower dissected to show reproductive structures Stamens (male) produce pollen Carpel (female) produces eggs

16. Cross Fertilization of Parents True-breeding Purple-flowered Parent True-breeding White-flowered Parent Cross-Fertilize All Purple-flowered Offspring Pollen Pollen P P F 1

17. Self-fertilization of F 2 F 1 Self-Fertilize F 2 F 2 F 2 F 2 75% Purple 25% White

21. Gametes of Homozygotes A A Homozygous Parent Gametes All gametes identical regarding this gene A A

22. Gametes of Heterozygotes A a Heterozygous Parent Gametes Gametes 50/50 regarding this gene A a

23. Homozygous Dominant X Homozygous Recessive pp homozygous recessive P p P p Purple Parent PP homozygous dominant White Parent sperm nuclei egg nuclei sperm nuclei egg nuclei

24. P Sperm + p Eggs same as p Sperm + P Eggs Pp pP Purple F 1 Purple F 1 P p sperm nucleus egg nucleus + p P egg nucleus sperm nucleus +

25. Pp X Pp Cross Purple homozygous dominant (PP) Purple heterozygous (Pp) Purple heterozygous (pP) White homozygous recessive (pp) P p p P p P P p + + + + F 1 Sperm F 1 Eggs F 2 Offspring

28. Making a Punnett Square: Heterozygous X Heterozygous P p 1(25%) White 3 (75%) Purple Eggs of Heterozygous Plant Pollen of Heterozygous Plant 1 1 P p p P P p P P p p Frequencies Phenotypes Genotypes Frequencies 2 PP p p p P P p

31. Test Cross: Heterozygous X Homozygous Recessive p p (50%) White (50%) Purple Eggs of Homozygous Recessive Pollen of unknown plant with dominant phenotype (Heterozygous) P p p p P p P P p p Frequencies Phenotypes Genotypes Frequencies 2 Pp p p p P p p 2

32. Test Cross: Homozygous X Homozygous Recessive p p (100%) Purple Eggs of Homozygous Recessive Pollen of unknown plant with dominant phenotype (Homozygous) P P p P p P p P p P Frequencies Phenotypes Genotypes Frequencies Pp P p P p P p 4

33. Traits of Peas Studied by Mendel Plant size Flower location Flower color Pod color Pod shape Seed shape Seed color

36. Dihybrid Cross: S s Y y X S s Y y SY S y s Y sy SsYy Parent Self-fertilizes 1 4 1 4 1 4 1 4 SY S y s Y sy 1 4 1 4 1 4 1 4 Eggs Sperm 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 1 16 SSYY SSY y S s YY S s Y y SS y Y SS yy S sy Y S syy s SYY s SY y ss YY ss Y y s S y Y s S yy ssy Y ssyy

39. Independent Assortment Meiosis II Meiosis I Randomly one or the other Chromosome Replication Y S S Y y s s y y S S y Y s Y s S y y S Y Y s s S s Y y S s Y y Y y S s Y Y S s y y S s S Y Y S s y y s

41. Linkage Red Allele, p Round Allele, l Purple Allele, P Long Allele, L Flower color gene Pollen shape gene

43. Crossing Over red red Purple Purple round round Long Long Sister Chromatids Sister Chromatids old combination new combination new combination old combination P P p p L L l l P p p L L l l P L p L l l P p P L p L l l P p L L l l P P p p P P p p L L l l P p p L L l l Duplicated Chromosome Duplicated Chromosome L L l l P P p p Homologous Chromosomes P P p p L L l l P p p L L l l p L P l L P l p Flower Color Pollen Shape

50. Sex Determination in Mammals X 1 X 2 EGGS Male Parent Y X m S P E R M Female Offspring Male Offspring Y X m X m X 1 X 2 X m Y Y X 1 X 2 X 1 X 2 Female Parent

54. Sex Linkage: Eye Color in Fruit Flies 25% Normal f Carrier f Normal m 25% 25% 25% White-e m Eggs of X R X r Female Sperm of X R Y Male 1 1 Y X R X R X r X R X R Y X r Female Female Male Male 1 1 Frequencies Phenotypes Genotypes Frequencies X R X R X r Y X R X r X R Y R r R

57. Incomplete Dominance: Homozygous-X Homo Recessive R R (100%) Pink (intermediate) Eggs of Homozygous RR Red Parent Pollen of Homozygous R ' R ' White Parent R' R' R' R R' R R' R R' R Pink Pink Pink Pink 1 Frequencies Phenotypes Genotypes Frequencies R'R R'R R'R R'R

58. Incomplete Dominance: F 1 X F 1 (25%) (25%) Red White R R' (50%) Pink Eggs of Heterozygous RR ' Pink F 1 Parent Pollen of Heterozygous RR ' Pink F 1 Parent R R' R' R R R' R R R' R' 1 1 Red Pink Pink White Frequencies Phenotypes Genotypes Frequencies RR R'R' RR' R'R 2

59. Human Eye Color AB Ab aB ab AB Ab aB ab EGGS SPERM Mother AaBb Father AaBb AABB AABb AaBB AaBb black dark brown dark brown light brown AAbB dark brown AAbb light brown AabB light brown Aabb blue aABB aABb aaBB aaBb dark brown light brown light brown blue aABb aABb aaBb aabb light brown blue blue light blue

64. Human ABO Blood Group 10% 40% 46% 4% B or AB A or AB O,AB, A,B (universal) AB (universal) B or O A or O O AB, A, B, O (universal) A B Both Neither BB or BO AA or AO OO AB O AB B A Freq Donates Re- ceives Anti- bodies RBCs Genotype Type

71. How to Read Pedigrees = male = female = parents or = individual who shows the trait or = heterozygous carrier of autosomal trait = offspring 1 2 3 I, II, III, IV, or V = generation

72. A Recessive Pedigree

73. Pedigrees: Legacy of Queen Victoria

75. Normal Red Blood Cells

76. Sickled Cells

80. Non-Disjunction Incorrect separation of chromosomes or chromatids in meiosis known as non-disjunction Most embryos arising from gametes with abnormal chromosome numbers abort spontaneously (are miscarried) Some combinations of abnormal chromosome number survive to birth or beyond

83. Incidence of Down Syndrome Age of Mother (years) Number per 1000 Births 10 20 30 40 50 0 100 200 300 400

84. The end