Warm-up: 12/9 With Pea Plants which is dominant, purple flower or white flower? What does P1 generation mean? What does purebred mean For flower color what does the F1 generation look like in terms of dominant vs recessive trait?
Mendel Cont. pp. 177-181
Mendel’s Experiment Review: Grew plants for pure traits (i.e. purple always produces purple) via self-pollination to make a pure strain (P1 generation) Cross-pollination of pure strains (P cross) PFP with WFP Counted the offspring (F1 generation) Self-pollination of the F1 generation to create the F2 generation
Mendel’s results One trait was masked by a dominant factor and the trait that did not appear (in F1 but did in F2) was recessive Trait controlled by a recessive factor is masked when paired with a dominant
Chromosomes and genes Gene (located on a chromosome) codes for a characteristic (ie flower color) Different forms of a gene = allele (purple or white) Letters used to represent alleles dominant trait capitalized (purple = P) recessive lower case (white = p)
Genotypes and Phenotypes Genotype: alleles an organism inherits EX: PP Pp pp Phenotypes: appearance due to the genotype EX: PP (purple) Pp (purple) pp (white) Homozygous: both alleles are alike (PP or pp) Heterozygous: alleles are different
Rules Law of segregation: paired factors separate during meiosis (formation of gametes) Law of independent assortment: alleles sort independently of one another (not all dominant appeared together)
Punnett Squares pp. 180-183
Monohybrid cross: cross between individuals that looks at one trait Punnett square: diagram to predict the probability of inheritance of certain traits Parent I B b B Parent II b
Place the parent genotypes in: Bb x Bb Match letters and fill in squares Parent I B b B BB Bb Parent II b Bb bb
Mendel’s Ratios from his experiments What are the Genotypes? What is the genotype ratio? What are the Phenotypes? What is the Phenotype ratio?
Mendel’s Ratios from his experiments Genotype ratio 1:2:1 Phenotype ratio 3:1
Mendel’s Ratios from his experiments Genotype ratio 1:2:1 Phenotype ratio 3:1
Genotype ratio ? 1: 1 Phenotype ratio ? All black