<unk> s are<unk> s which contain the same genes in the same order along their<unk> l arms. There are two main properties of<unk> s: 1) the length of<unk> l arms and 2) the placement of the centromere. The actual length of the arm, in accordance with the gene locations, is critically important for proper alignment. Centromere placement on the<unk>  can be characterized by four main arrangements, either metacentric, submetacentric, acrocentric, or telocentric. Both of these properties (i.e., the length of<unk> l arms, and the placement of the<unk> l centromere) are the main factors for creating structural homology between<unk> s. Therefore, when two<unk> s containing the relatively same structure exist (e.g., maternal<unk>  15 and paternal<unk>  15), they are able to pair together via the process of synapsis to form<unk> s. Since<unk> s are not identical and do not originate from the same organism, they are different from sister chromatids. Sister chromatids result after DNA replication has occurred, and thus are identical, side-by-side duplicates of each other. In humans Humans have a total of 46<unk> s, but there are only 22 pairs of<unk>  autosomal<unk> s. The additional 23rd pair is the sex<unk> s, X and Y. Note that the pair of sex<unk> s may or may not be<unk> , depending on the sex of the individual. For instance, females contain XX, thus have a<unk>  pair of sex<unk> s. This means that females have 23 pairs of<unk> s in total (i.e., 22 pairs of non-sex<unk> s (autosomes), 1 pair of sex<unk> s). Conversely, males contain XY, which means that they have a non-homologous pair of sex<unk> s as their 23rd pair of<unk> s. In humans, the 22 pairs of<unk>  autosomal<unk> s contain the same genes but code for different traits in their allelic forms, as one was inherited from the mother and one from the father. So, humans have two sets of 23<unk> s in each cell that contains a nucleus. One set of 23<unk> s (n) is from the mother (22 autosomes, 1 sex<unk>  (X only)) and one set of 23<unk> s (n) is from the father (22 autosomes, 1 sex<unk>  (X or Y)). Ultimately, this means that humans are diploid (2n) organisms.
Homologous chromosome
Sex chromosome
Nuclear gene
Active chromatin sequence
Chimeric gene
Satellite chromosome
Marker chromosome
Epigenetics