Final answer:
Non-homologous chromosomes are those that do not pair up during meiosis and carry different genes, contrasting homologous chromosomes that pair up and have genes at the same loci. Nondisjunction may occur leading to aneuploidy in gametes.
Step-by-step explanation:
Definition of Non-homologous Chromosomes
Non-homologous chromosomes are chromosomes that do not pair during meiosis. Unlike homologous chromosomes which are pairs of chromosomes in a diploid organism that have the same length, gene order, and loci, non-homologous chromosomes carry different genes. These are not the matched pairs and do not synapse during meiosis, which is the process through which gametes (sex cells) are created. This distinction is critical in the context of genetic variation and the segregation of chromosomes during meiosis.
It's important to note concepts such as nondisjunction, which is the failure of homologous chromosomes to separate during meiosis I or of sister chromatids to separate during meiosis II. This leads to aneuploidy, a condition where gametes have an abnormal number of chromosomes, either lacking some (n-1) or having extra (n+1), which can lead to chromosomal aberrations in the resultant offspring.