1. UNIT 3 The transmission of traits Biology and Geology. Secondary Education. THE CHROMOSOME THEORY OF INHERITANCE

2. UNIT 3 The chromosome theory of inheritance Biology and Geology. Secondary Education. From 1900 (when Mendel’s laws were rediscovered) onwards, modern genetics began to develop further, and the role of chromosomes as the carriers of genes was proposed. In1902, Sutton and Boveri formulated the idea that Mendel’s factors of heredity were to be found in chromosomes.

3. UNIT 3 The chromosome theory of inheritance Biology and Geology. Secondary Education. If chromosomes are carriers of hereditary elements or genes, then we can presume that when they are separated during meiosis, each element of the pair passes to different cells; each cell, therefore, carries only one element of the pair, that of the mother or that of the father. This behaviour is in accordance with the first of Mendel’s laws.

4. UNIT 3 The chromosome theory of inheritance Biology and Geology. Secondary Education. In 1909, Johannsen was the first to use the terms gene, genotype and phenotype, but it was Thomas Hunt Morgan who established a series of fundamental principles, using a new experimental methodology. Morgan worked with the Drosophila melanogaster fruit fly and established that genes form part of chromosomes, and can be located within specific places, called locus or loci. This theory is known as the chromosome theory of inheritance. T.H. Morgan