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[...]... - Smooth (S) or wrinkled (s) Pod Color - Green (G) or Yellow (g) Seed Coat Color -Gray (G) or White (g) Flower position -Axial (A) or Terminal (a) Plant Height - Tall (T) or Short (t) Flower color - Purple (P) or white (p) copyright cmassengale 21 copyright cmassengale 22 copyright cmassengale 23 Mendel s Experimental Results copyright cmassengale 24 Did the observed ratio match the theoretical... wrinkled Mendel s observed ratio was 2.96:1 The discrepancy is due to statistical error The larger the sample the more nearly the results approximate to the theoretical ratio copyright cmassengale 25 Generation “Gap” Parental P1 Generation = the parental generation in a breeding experiment F1 generation = the first-generation offspring in a breeding experiment (1st filial generation) From breeding individuals... artificially cross-pollinated copyright cmassengale 17 Reproduction in Flowering Plants Pollen contains sperm Produced by the stamen Ovary contains eggs Found inside the flower Pollen carries sperm to the eggs for fertilization Self-fertilization can occur in the same flower Cross-fertilization can occur between flowers copyright cmassengale 18 Mendel s Experimental Methods Mendel hand-pollinated flowers... Designer “Genes” Alleles - two forms of a gene (dominant & recessive) Dominant - stronger of two genes expressed in the hybrid; represented by a capital letter (R) Recessive - gene that shows up less often in a cross; represented by a lowercase letter (r) copyright cmassengale 11 More Terminology Genotype - gene combination for a trait (e.g RR, Rr, rr) Phenotype - the physical feature resulting... to prevent self-pollination Covered each flower with a cloth bag He traced traits through the several generations copyright cmassengale 19 How Mendel Began Mendel produced pure strains by allowing the plants to selfpollinate for several generations copyright cmassengale 20 Eight Pea Plant Traits Seed shape - Round (R) or Wrinkled (r) Seed Color Yellow (Y) or Green (y) Pod Shape - Smooth (S) or... = the first-generation offspring in a breeding experiment (1st filial generation) From breeding individuals from the P1 generation F2 generation = the second-generation offspring in a breeding experiment (2nd filial generation) From breeding individuals from the F1 generation copyright cmassengale 26 Following the Generations Cross 2 Pure Plants TT x tt Results Cross 2 Hybrids in all get Hybrids 3... cmassengale 13 Genotypes Homozygous genotype - gene combination involving 2 dominant or 2 recessive genes (e.g RR or rr); also called pure Heterozygous genotype - gene combination of one dominant & one recessive allele (e.g Rr); also called hybrid copyright cmassengale 14 Genes and Environment Determine Characteristics copyright cmassengale 15 Mendel s Pea Plant Experiments copyright cmassengale... Recessive rr Offspring called F2 generation Genotypic ratio is 1:2:1 Phenotypic Ratio is 3:1 copyright cmassengale 32 What Do the Peas Look Like? copyright cmassengale 33 …And Now the Test Cross Mendel then crossed a pure & a hybrid from his F2 generation This is known as an F2 or test cross There are two possible testcrosses: Homozygous dominant x Hybrid Homozygous recessive x Hybrid copyright