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1 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Petals Carpel (female) Stigma Style Anthers (male) 1. The anthers are cut away on the purple flower. 2. Pollen is obtained from the white flower. 3. Pollen is transferred to the purple flower. 4. All progeny result in purple lowers. © Leslie Holzer/Photo Researchers, Inc. 3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dominant Recessive F2 Generation 1. Flower Color 705 Purple: 224 White X 3.15:1 Purple White 2. Seed Color 6022 Yellow: 2001 Green X Yellow Green 3.01:1 3. Seed Texture 5474 Round: 1850 Wrinkled X 2.96:1 Round Wrinkled 4. Pod Color 428 Green: 152 Yellow X 2.82:1 Green Yellow 5. Pod Shape 882 Inflated: 299 Constricted X 2.95:1 Inflated Constricted 6. Flower Position 651 Axial: 207 Terminal X 3.14:1 Axial Terminal 7. Plant Height 787 T all: 277 Short X 2.84:1 Tall Short 4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Truebreeding Purple Parent Truebreeding White Parent Parent generation Cross-fertilize Purple Offspring F1 generation Self-cross Purple Dominant Purple Dominant Purple Dominant White Recessive Truebreeding Non-truebreeding Non-truebreeding Truebreeding Self-cross Self-cross Self-cross Self-cross F2 generation (3:1 phenotypic ratio) F3 generation (1:2:1 genotypic ratio) 5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P p P P P p pp P P White parent pp Purple parent PP pp P 2. P + p = Pp. p Pp P P PP p p Pp p 1. p + p = pp. p Pp Pp Pp Pp P p Pp F1 generation p pP 3. p + P = pP. pp p pP pp Purple heterozygote Pp 4. P + P = PP. a. p P Purple heterozygote Pp P PP Pp pP pp p F2 generation 3 Purple:1 White (1PP: 2Pp :1pp ) b. 6 7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dominant Pedigree Generation I 1 2 2 3 Generation II 1 4 5 2 3 Generation III 1 Key unaffected male affected male unaffected female affected female 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Recessive Pedigree One of these persons is heterozygous Generation I 1 2 Heterozygous Generation II 1 2 3 4 5 Generation III 1 Generation IV 2 3 4 5 6 7 Mating between first cousins 1 2 3 Homozygous recessive Key unaffected male affected male male carrier unaffected female affected female female carrier 9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. RR YY rr yy Meiosis Meiosis Parent generation Cross-Fertilization Rr Yy F1 generation Meiosis (chromosomes assort independently into four types of gametes) RY Ry rY ry F1 X F1 (RrYy X RrYy) RY RY F2 generation Ry rY RR YY RR Yy Rr YY Ry RR Yy rY Rr YY ry Rr Yy RR yy Rr Yy Rr Yy rr YY Rr yy rr Yy ry Rr Yy 9/16 Rr yy rr Yy rr yy round, yellow 3/16 round, green 3/16 wrinkled, yellow 1/16 wrinkled, green 10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Dominant Phenotype (unknown genotype) Homozygous recessive p Homozygous dominant Homozygous recessive p p Heterozygous dominant P Pp Pp P Pp Pp Alternative 1: All offspring are purple and the unknown flower is homozygous dominant P PP or Pp? If PP If Pp then then p Pp Pp pp pp p Alternative 2: Half of the offspring are white and the unknown flower is heterozygous dominant 11 12 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. SCIENTIFIC THINKING Hypothesis: The pink F1 observed in a cross of red and white Japanese four o’clock flowers is due to failure of dominance and is not an example of blending inheritance. Prediction: If pink F1 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. CRCR CWCW Parent generation Cross-fertilization CRCW F1 generation CR CW CRCR CRCW CRCW CWCW CR F2 generation CW 1:2:1 CRCR: CRCW: CWCW Result: When this cross is performed, the expected outcome is observed. Conclusion: Flower color in Japanese four o’clock plants exhibits incomplete dominance. Further Experiments: How many offspring would you need to count to be confident in the observed ratio? 14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Alleles IAIA, IAi (IA dominant to i) IBIB, IBi (IB dominant to i) IAIB (codominant) ii (i is recessive) Blood Type Sugars Exhibited Donates and Receives A Galactosamine Receives A and O Donates to A and AB B Galactose Receives B and O Donates to B and AB Both galactose and galactosamine Universal receiver Donates to AB None Receives O Universal donor AB O 15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. temperature below 33°C, tyrosinase active, dark pigment Temperature above 33°C, tyrosinase inactive, no pigment © DK Limited/Corbis. 16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. White (AAbb) White (aaBB) Cross-fertilization Parental generation All Purple (AaBb) F1 generation AB Ab aB ab AABB AABb AaBB AaBb AABb AAbb AaBb Aabb AaBB AaBb aaBB aaBb AaBb Aabb aaBb aabb AB Ab F2 generation aB ab 9/16 Purple: 7/16 White a. Precursor (colorless) b. Enzyme A Intermediate (colorless) Enzyme B Pigment (purple) 17