1 2 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stigma Style Anthers (male) 4. All progeny result in purple lowers. 3. Pollen is transferred to the purple flower. 2. Pollen is obtained from the white flower. 1. The anthers are cut away on the purple flower. Petals Carpel (female) Leslie Holzer/Photo Researchers, Inc. 3 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. PurpleWhite YellowGreen RoundWrinkled GreenYellow 1. Flower Color 2. Seed Color 4. Pod Color DominantRecessive 3.15:1 X X X X 3.01:1 2.96:1 2.82:1 InflatedConstricted 5. Pod Shape X 2.95:1 AxialTerminal TallShort 6. Flower Position 7. Plant Height X X 3.14:1 2.84:1 F 2 Generation 705 Purple: 224 White 6022 Yellow: 2001 Green 5474 Round: 1850 Wrinkled 428 Green: 152 Yellow 882 Inflated: 299 Constricted 651 Axial: 207 Terminal 787 T all: 277 Short 3. Seed Texture 4 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Parent generation Self-cross Cross-fertilize Self-cross True- breeding Purple Parent True- breeding White Parent Purple Offspring F 1 generation F 2 generation (3:1 phenotypic ratio) F 3 generation (1:2:1 genotypic ratio) Purple Dominant Purple Dominant Purple Dominant White Recessive True- breeding Non-true- breeding Non-true- breeding True- breeding 5 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P P p ppp P P p p Pp P P p ppppP P P p ppp Pp pP PpPP a. p P p P Pp White parent pp b. P P p p pp Pp Purple parent PP Purple heterozygote Pp 1. p + p = pp.2. P + p = Pp. 3. p + P = pP.4. P + P = PP. Purple heterozygote Pp F 1 generation PP pP F 2 generation 3 Purple:1 White (1PP: 2Pp :1pp ) 6 7 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dominant Pedigree Key Generation I Generation II Generation III unaffected male unaffected female affected male affected female 8 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Recessive Pedigree Key male carrier female carrier Generation I Generation II Generation III Heterozygous Homozygous recessive Generation IV unaffected male unaffected female affected male affected female One of these persons is heterozygous Mating between first cousins 9 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. RYRyrYry RR yyRr yy rr yy 9/16 3/16 1/16 round, yellow round, green wrinkled, yellow wrinkled, green Cross-Fertilization RY Ry rY ry RYRyrYry Meiosis rr yy Parent generation RR YY Rr Yy F 1 generation Meiosis (chromosomes assort independently into four types of gametes) F 1 X F 1 (RrYy X RrYy) F 2 generation RR YYRR YyRr YYRr Yy RR YyRr Yy rr Yy rr YYRr YyRr YY Rr Yy 10 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. p P p P Pp If PpIf PP then p P p p pp Pp pp Pp Dominant Phenotype (unknown genotype) Homozygous recessive Heterozygous dominant Alternative 2: Half of the offspring are white and the unknown flower is heterozygous dominant Alternative 1: All offspring are purple and the unknown flower is homozygous dominant Homozygous recessive Homozygous dominant PP or Pp? 11 12 13 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Parent generation 1 : 2 : 1 CRCR CWCW Cross-fertilization CWCWCWCW CRCRCRCR SCIENTIFIC THINKING Hypothesis: The pink F 1 observed in a cross of red and white Japanese four oclock flowers is due to failure of dominance and is not an example of blending inheritance. Prediction: If pink F 1 are self-crossed, they will yield progeny thesame as the Mendelian monohybrid genotypic ratio. This would be1 red: 2 pink: 1 white. Test: Perform the cross and count progeny. F 1 generation Result: When this cross is performed, the expected outcome is observed. Conclusion: Flower color in Japanese four oclock plants exhibits incomplete dominance. Further Experiments: How many offspring would you need to count to be confident in the observed ratio? CRCWCRCW CRCWCRCW CRCRCRCR CRCR CWCW CRCWCRCW CWCWCWCW C R C R : C R C W : C W C W F 2 generation 14 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Alleles AB None O Galactosamine A Galactose B Blood Type Sugars Exhibited Donates and Receives Receives A and O Donates to A and AB Receives B and O Donates to B and AB Universal receiver Donates to AB Receives O Universal donor Both galactose and galactosamine I A I A, I A i (I A dominant to i) I B I B, I B i (I B dominant to i) I A I B (codominant) ii (i is recessive) 15 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Temperature above 33C, tyrosinase inactive, no pigment temperature below 33C, tyrosinase active, dark pigment DK Limited/Corbis. 16 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ABAbaBab AABBAABbAaBBAaBb AABbAAbbAaBbAabb AaBBAaBbaaBBaaBb AaBbAabbaaBbaabb 9/16 Purple: 7/16 White AB Ab aB ab Cross-fertilization a. b. Parental generation F 1 generation F 2 generation Pigment (purple) Enzyme B Enzyme A Precursor (colorless) Intermediate (colorless) White (aaBB) White (AAbb) All Purple (AaBb) 17