For the purple flower plant or white flowers for the

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for the purple flower plant or white flowers for the white flower plant o Means that the genotypes are homozygous o Genotype: Purple flower plant: P/P Homozygous for the dominant allele P White flower plant: p/p Homozygous for the recessive allele p o Gametes: Purple flower: P Can only produce gamete with P allele o Only has purple alleles so can only produce purple gametes White flower: p Can only produce gamete with p allele o Only has white alleles so can only produce white gametes *If cross these 2 plants, will have purple alleles in one gamete and white alleles in the other gamete and that will give the offspring First Filial Generation (F1) o Genotype: P/p All would be heterozygous Got P from purple flower and p from white flower o Phenotype: all Purple Because purple is dominant to white in a heterozygous condition, that means phenotypically all of the plants will be purple flowers Will look just like the homozygous dominant plants (same color purple) F2 Generation o Would make the F2 generation by crossing 2 F1s, so the cross would be P/p to P/p o Cross: P/p X P/p o Gamete: P or p and P or p Each genotype can produce P or p since it is heterozygous and contains both P and p Half the gametes will have P and half will have p Tricky part: put all gametes together and form all possible genotypes to make F2 generations Use Punnett Square to do this 24
o In a punnett square, put the gametes that one individual can produce on one axis and the gametes that other individual can produce on the other axis o After that, you combine them together Can also think of the genotypes in terms of flower color Homozygous dominant and heterozygous: purple flowers Homozygous recessive: white flowers Means that there are variations in the genotypes of the offspring for F2 and in the phenotype for F2 The ratios are somewhat different o Ratios of Offspring Genotypic ratio: 1 P/P: 2 P/p: 1 p/p Phenotypic ratio: 3 purple flowered: 1 white flowered 25
Test Cross Cross an individual of an unknown genotype with a homologous recessive individual Which phenotype has an unknown genotype? o Dominant Dihybrid Cross (Seed Form and Seed Color) Dihybrid cross: cross that involves two different genes (traits) o Humans are result of thousands of crosses simultaneously Parental Generation (P) o Phenotype: Round Yellow X Wrinkled Green Parent 1: Round Yellow Parent 2: Wrinkled Green o Genotype: Round Yellow: R/R Y/Y Round part comes from R/R (homozygous dominant for seed form) Yellow part comes from Y/Y(homozygous dominant for seed color) Wrinkled Green: r/r y/y Wrinkled part comes from r/r (homozygous recessive for seed form) Green part comes from y/y (homozygous recessive for seed color) o Gametes: R/Y Produced from R/R Y/Y r/y Produced from r/r y/y F1 Generation o Genotype: R/r Y/y Double heterozygous R and r and Y and y Heterozygous for both genes o Phenotype: all Round Yellow seeded o Gametes: R/Y, R/y, r/Y, r/y

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