3.4Genetic Factors and Chromosomes
As mentioned above, Mendel believed that individual genetic traits are determined by two paired factors; one of these factors is distributed to each of the gametes (reproductive cells) and then reunited by fertilization. At that time, more detailed data for explaining this observation could not be obtained; however, chromosomes, the aggregates of genes, were discovered later. Chromosomes are halved during meiosis and subsequently reconstituted to their original form by fertilization. Thus, these factors were found to be present in chromosomes. Moreover, two paired chromosomes are segregated independent of other chromosome pairs. This random arrangement of chromosomes is reflected through Mendel’s law of independent assortment because genes on different chromosomes will be inherited independently.