Chapter 10

Stigma (receives pollen) SELF-POLLINATION Anthers (produce pollen grains, which contain male gametes) Ovules (produce female gametes) Figure 10.1a Self-pollination

1. Remove anthers from one plant. 2. Collect pollen from a different plant. 3. Transfer pollen to a stigma of the individual whose anthers have been removed. Figure 10.1b CROSS-POLLINATION

Trait Phenotypes Seed shape Round Wrinkled Seed color Pod shape Pod color Yellow Green Inflated Green Constructed Yellow Figure 10.2 upper

Trait Phenotypes Flower color PurpleWhite Axial (on stem)Terminal (at tip) Flower and pod position Stem length TallDwarf Figure 10.2 lower

Pollen from round- seeded parent… …to stigma of wrinkled-seeded parent All progeny have round seeds Figure 10.3a First half of reciprocal cross

All progeny have round seeds Round-seeded parent receives pollen... …from wrinkled- seeded parent Figure 10.3b Second half of reciprocal cross

Results of second generation crosses Mendel found that the recessive traits reappeared in some individuals He found 14,949 plants in his second generation with the dominant trait and 5,010 with the recessive trait This ratio of 2.98 to 1 suggests a three- to-one ratio

R Mother Rr Female gametes R r Father Rr Male gametes R r RrRR Rrrr Resulting genotypes: 1/4 RR : 1/2 Rr : 1/4 rr Resulting phenotypes: 3/4 : 1/4 Figure 10.7 R = Dominant allele for seed shape (round) r = Recessive allele for seed shape (wrinkled) = Round-seeded phenotype = Wrinkled-seeded phenotype

Chapter 9

Meiosis is a Special Type of Cell Division that Occurs in Sexually Reproducing Organisms Meiosis reduces the chromosome number by half, enabling sexual recombination to occur. Meiosis of diploid cells produces haploid daughter cells, which may function as gametes.

Each chromosome replicates prior to undergoing meiosis. Maternal chromosome Centromere Homologous pair of premeiotic chromosomes Duplication Paternal chromosome Sister chromatids Figure 9.2a

During meiosis, chromosome number in each cell is reduced. Parent cell contains homologous pair of chromosomes MEIOSIS I Homologs separate Sister chromatids separate Daughter cells contain just one homolog Four daughter cells contain one chromosome each. These cells become gametes. MEIOSIS II Figure 9.2b

A full complement of chromosomes is restored during fertilization. Female gamete Fertilization Diploid offspring contains homologous pair of chromosomes Male gamete Figure 9.2c

R Mother Rr Female gametes R r Father Rr Male gametes R r RrRR Rrrr Resulting genotypes: 1/4 RR : 1/2 Rr : 1/4 rr Resulting phenotypes: 3/4 : 1/4 Figure 10.7 R = Dominant allele for seed shape (round) r = Recessive allele for seed shape (wrinkled) = Round-seeded phenotype = Wrinkled-seeded phenotype