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chromosomes

noun, plural of chromosome

Chromosomes are gene-bearing structures within cells made up of DNA packaged by various proteins into a compact unit. Chromosomes are chromatins that have rolled up and compacted particularly at the time of cell division. They are found in the nucleus of eukaryotic cells and in nucleoid of prokaryotic cells.

In eukaryotes, the chromosomes appear as threadlike strand that condense into thicker structures and aligns on the metaphase plate during mitosis. In human somatic cells, chromosomes occur in pairs; in fact, humans have 23 pairs of chromosomes, each with a characteristic length and banding pattern. One of these pairs determines the sex of humans: the X chromosome and the Y chromosome. Males have X and Y chromosomes whereas females have 2 X chromosomes.

In most prokaryotes, the chromosome is usually a circular strand of DNA; hence, the entire genome is carried on only one chromosome. In viruses, the chromosome may appear as short linear or circular structure containing the DNA or RNA molecule often lacking any structural proteins

Word origin: from the Greek chroma = color + soma = body