Mendel’s Principles of Inheritance and the Chromosome Theory

Inheritance is a fundamental feature of all organisms. A critical question is how our genes and traits are transmitted to the next generations. In 1866, Gregor Mendel published the basic principles of inheritance from his studies on the hybridization of garden peasgarden peas. This chapter will discuss Mendel’s experiments using seven plant variants and his interpretations of the data. Mendel’s laws of dominance, segregation, and independent assortmentindependent assortment were confirmed long after his death, first in plants and later in Drosophila and other organisms. We will also discuss the limitations of Mendel’s data for the independent assortment. Following Mendel’s findings, Drosophila emerged as a powerful genetic model organism through the work of Thomas Hunt MorganMorgan and his students. The isolation of a white-eye mutant fly led to the idea of sex-linked genes. A critical question was the relationship between genetic factors and chromosomes. The chromosome theorychromosome theory was investigated by genetic and cytological analysis of the white mutationmutationwhite and chromosomal non-disjunction. We will discuss how the chromosome theory was proved in Drosophila. Mendel’s principles and the chromosome theory have laid the foundation of modern genetics.