ANT E101 Lecture Notes - Lecture 4: Phenotype, Organelle, Pisum
Document Summary
All organisms have descended with modification from common ancestors. Mechanism for evolutionary change is the action of natural selection on individual variation. Pre-dna concepts of heredity: blending theory of inheritance. Each parent contributes equally to the offspring and the contributions are halved at each successive generation. Blending inheritance: parental contribution is averaged out, or blended, in offspring. Undertook a systematic investigation of inheritance using very large numbers of pea plants. It shows variation in a number of different traits. Although most plants are hermaphrodite (have both male and female organs), cross- fertilization is achieved via cross-pollution. F1 (first filial) generation: all progeny had yellow seeds, despite variation among parents. He always found that the f1 generation was homogeneous in its expression and it matched the expression in one of the parents. Each hereditary characteristic is controlled by particulate unit factors, which exist in pairs in individual organisms; one factor is inherited from each parent.
