= Chromosome
{wiki}
A chromosome carries <genes> and other genetic material. A <haplotype> records the <alleles> carried on one chromosome at specified <genetic loci>.
In a typical <eukaryotic> <cell nucleus>, an unreplicated <chromosome> comprises one long double-stranded <DNA> <molecule> with associated <proteins>; a replicated <chromosome> comprises two associated <sister chromatids>. It need not be X-shaped: that familiar outline depicts a condensed, replicated state.<Biology 2e by Mary Ann Clark and others/Cell Division>[Biology 2e by Mary Ann Clark and others; §10.1, Genomic DNA; Eukaryotic Chromosomal Structure and Compaction, especially Figure 10.4 and final paragraph]{ref}
For these ordinary <centromere>-bearing <chromosomes>, count by <centromere> units before separation: the paired sister <centromere> regions count together as one replicated <chromosome>. Once <sister chromatids> separate in <anaphase> of <mitosis> or <meiosis II>, each becomes a daughter <chromosome>. Thus the undivided <anaphase> <biological cell> in the $2n=6$ mitotic example transiently contains twelve daughter <chromosomes>, but each pole receives six and each completed daughter <cell nucleus> remains <diploid>. State the counting compartment and stage; summing both poles is not the <ploidy> of one daughter.
Back to article page
