(August 2004) Genetics and sex determination Genetics is defined as the study of genes. Genes are composed of deoxyribonucleic acid (DNA) that can be passed down and inherited from one generation to the next. The information encoded in DNA is critical for determining the properties of a species1. DNA is divided into discrete molecules called chromosomes, each of which contain numerous genes. Figure 1. Non-disjunction during meiosis II results in two normal gametes, one n+1 gamete, and one n-1 gamete. A ‘normal’ human cell is diploid (2n) because it contains 2 copies of each of the 23 chromosomes. Included in…