Mendel's Principle Of Segregation Analysis

Gregor Mendel wondered is his principle of segregation worked with individuals who differed in two traits. To test this, Mendel crossed pure lined round, yellow seeds with pure lined wrinkled, green seeds. He predicted that the F_1 offspring would be heterozygous for both genes. Experiments had established that the allele for yellow seeds were the dominant allele (Y) and green seeds were the recessive allele (y). There were two different ways as to how seed shape and seed color would be passed onto offspring. One was independent assortment, which says that the allele for seed shape and the allele for seed color present in each parent would assort independently. Another was dependent assortment, which says that the alleles for seed color and
They thought Mendel’s hereditary determinants were on a locus. They found out that the physical separation of alleles during anaphase I of meiosis accounts for Mendel’s principle of segregation. If the alleles for different genes are located on different chromosomes, they assort independently from one another in meiosis I. This confirmed the principle of independent assortment. Later on, the two scientists came up with the chromosome theory of inheritance, which states that independent assortment happens in metaphase and anaphase of meiosis I. To test the theory of inheritance, scientist Thomas Hunt Morgan used the fruit fly. At one point, Morgan noticed that a male fruit fly had white eyes rather than the wild type red eyes. He concluded that the white eyes resulted from a mutation. He mated a red-eyed female with a mutant white-eyed male and the results showed that all of the F_1 females had red eyes, but the F_1 males had white eyes. This was very peculiar because Mendel already proved that traits are not sex based. Morgan realized that the X chromosome in males and females explained his results. He determined that eye color is carried on the X chromosome and not on the Y chromosome. This is described as sex-linked inheritance. According to the X-linkage hypothesis, a female has two copies of the eye color gene because they have the two X chromosomes, whereas the male fruit flies have the one X chromosome that codes for eye color. The reciprocal cross of pea plants happened on non-sex chromosomes called autosomes. Genes on non-sex chromosomes show autosomal inheritance. Biologists now know that Boveri’s and Sutton's chromosome theory of inheritance was