BIOL 103 Lecture Notes - Lecture 29: Santa Barbara City College, Dihybrid Cross, Mendelian Inheritance
Document Summary
Phenotype: the observable characteristics resulting from genetic and environmental factors. Genotype: the genetic constitution of a trait. Continuous variation: seemingly infinite number of traits for a given character. These traits belong to a continuous spectrum (ex. skin color, weight, height etc) Discrete variation: there are only 2 to a few traits for a given character. Mendel crossed 2 true breeding pea plants and looked at one trait (phenotype) in the offspring; whether peas were spherical or wrinkled. He crossed spherical pea plants with wrinkled pea plants. This is termed a monohybrid cross which refers to a mating between individuals who have different alleles at one genetic locus of interest (pea morphology in this case). All peas of the first generation (f1) were spherical and none were wrinkled. Conclusion: the spherical seed trait is dominant over the wrinkled seed trait. The ratio of spherical peas to wrinkled peas in the second generation (f2) was 3:1.
