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homologous chromosome

noun

(Science: genetics)

1. one of a pair of chromosomes

2. a chromosome with the same gene sequence as another

3. In a biological cell, a chromosome pairs with another chromosome during meiosis. This pairing (synapsis) happens between two chromosomes that are homologous, i.e. chromosomes having the same genes at the same loci but possibly different alleles. For example, two chromosomes may have genes encoding eye color, but one may code for brown eyes, the other for blue.

• A human cell contains 23 pairs of homologous chromosomes: 22 of them are homologous non-sex chromosomes (or autosomes) and 1 homologous pair of sex chromosomes. In females, the homologous sex chromosomes are 2 X’s; in males the X and Y chromosomes.

(see plural form: homologous chromosomes)