Study of the concepts of determination/cell specification, differentiation and pattern formation. Sex determination in mammals and characterization of the SRY gene. Primery and secondary sexual differentiation in the human species. Development of the anteroposterior axis in Drosophila melanogaster. Homeotic genes in mammals. Developmental syndromes in humans. Cancer as a genetic disease. Oncogenes and tumor suppressor genes. The origin of cancer is due to accumulation of mutations in oncogenes and tumor suppressor genes.