Chromatid

A chromatid forms one part of a chromosome after it has coalesced for the process of mitosis or meiosis. During either process, the word "chromosome" indicates a pair of two exactly identical ("sister") chromatids joined at the central point of each chromatid, called the centromere.

Related Topics:
Chromosome - Mitosis - Meiosis - Centromere

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A chromosome, by definition, has exactly one centromere. Thus when sister chromatids are pulled apart by the mitotic spindle during anaphase -- that is, when the centromere joining two sister chromatids splits into two centromeres -- then each sister chromatid becomes an independent chromosome.

Related Topics:
Mitotic spindle - Anaphase

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In non-gametic, non-dividing human cells, there are 23 pairs of chromosomes, thus 46 chromosomes. When it is ready for mitosis cell divition, each chromosome will replicate itself during the Synthesis phase within its life cycle, making a total of 92 chromatids (remember, since the term "chromosome" is redefined, the number of chromosomes remains 46 despite the replication).

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In gametic, meiosis cell division, 23 chromosome are left in the egg cell or sperm cell. (as it needs 23chromosomes from male and female to make 46 chromosome for the zygote)

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