Chromatid

A chromatid holds the replicated DNA of each individual chromosome, which are joined by a centromere, for the process of cell division (mitosis or meiosis). They are normally identical ("homozygous") but may have slight differences in the case of mutations, in which case they are heterozygous. They are called sister chromatids so long as they are joined by the centromeres. When they separate (during anaphase of mitosis and anaphase 2 of meiosis), the strands are called daughter chromosomes (although having the same genetic mass as the individual chromatids that made up its parent, the daughter "molecules" are still referred to as chromosomes much as one child is not referred to as a single twin). Before replication, one chromosome is composed of one DNA molecule and after there are two DNA moles. This is because DNA replication increases the amount of DNA and does not increase the number of chromosomes.

In other words, a chromatid is "one-half of two identical copies of a replicated chromosome". The two copies may have slight differences due to mutations. A chromatid is simply a copied chromosome which is paired with a (normally) identical chromosome at the centromere. It should not be confused with the ploidy of an organism, which is the number of homologous versions of a chromosome.

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Other articles related to "chromatid, chromatids":

Sister Chromatid Exchange
... Sister chromatid exchange (SCE) is the exchange of genetic material between two identical sister chromatids ... It was first discovered by using the Giemsa staining method on one chromatid belonging to the sister chromatid complex before anaphase in mitosis ... The staining revealed that few segments were passed to the sister chromatid which were not dyed ...
Chromatid - Dyad
... A bivalent is a pair of sister chromatids ... After DNA replication, the two sister chromatids align side-by-side and appear to have an undivided centromere, in contrast to mitosis, in which each chromatid appears to have its own separate centromere ...
Sister Chromatids
... Sister chromatids are two identical copies of a chromatid ... Compare sister chromatids to homologous chromosomes, which are the two different copies of the same chromosome that diploid organisms (like humans) inherit, one ... In other words, sister chromatids contain the same genes and same alleles, and homologous chromosomes contain the same genes but two copies of alleles, each of which might or might not be the same as ...
Isochromosome
... During mitosis (or meiosis I or II), the sister chromatid sets line up along the midline in metaphase ... the long arm) of the affected chromatid (or vice versa) ... one arm of a chromosome and its homolog (or sister chromatid) at the proximal edge of the arm,adjacent to the centromere ...
Cohesin - Function
... It is used to keep the sister chromatids connected with each other during metaphase ensuring that during mitosis (and meiosis), each sister chromatid segregates to opposite poles ... Without cohesin, the cell would be unable to control sister chromatid segregation since there would be no way of ensuring whether the spindle fiber attached on each sister chromatid is from a different pole ...