Two identical copies of a chromosome joined at the centromere
The paternal (blue) chromosome and the maternal (pink) chromosome are homologous chromosomes. Following chromosomal DNA replication, the blue chromosome is composed of two identical sister chromatids and the pink chromosome is composed of two identical sister chromatids. In mitosis, the sister chromatids separate into the daughter cells, but are now referred to as chromosomes (rather than chromatids) much in the way that one child is not referred to as a single twin.Schematic karyogram of a human, showing a diploid set of chromosomes as seen in the G0 and G1 phases of the cell cycle (before DNA synthesis), including the chromosome 3 pair to the left in blue box at top center. To the right in that box, it also shows the chromosome 3 pair after DNA synthesis but before cell division (including the G2 phase and metaphase), wherein each paired "chromosome arm" is a sister chromatid.
Further information: Karyotype
A sister chromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common centromere. In other words, a sister chromatid may also be said to be 'one-half' of the duplicated chromosome. A pair of sister chromatids is called a dyad. A full set of sister chromatids is created during the synthesis (S) phase of interphase, when all the chromosomes in a cell are replicated. The two sister chromatids are separated from each other into two different cells during mitosis or during the second division of meiosis.
Compare sister chromatids to homologous chromosomes, which are the two different copies of a chromosome that diploid organisms (like humans) inherit, one from each parent. Sister chromatids are by and large identical (since they carry the same alleles, also called variants or versions, of genes) because they derive from one original chromosome. An exception is towards the end of meiosis, after crossing over has occurred, because sections of each sister chromatid may have been exchanged with corresponding sections of the homologous chromatids with which they are paired during meiosis. Homologous chromosomes might or might not be the same as each other because they derive from different parents.
There is evidence that, in some species, sister chromatids are the preferred template for DNA repair.[1]
Sister chromatid cohesion is essential for the correct distribution of genetic information between daughter cells and the repair of damaged chromosomes. Defects in this process may lead to aneuploidy and cancer, especially when checkpoints fail to detect DNA damage or when incorrectly attached mitotic spindles do not function properly.
^Kadyk, Lc; Hartwell, Lh (Oct 1992). "Sister chromatids are preferred over homologs as substrates for recombinational repair in Saccharomyces cerevisiae" (Free full text). Genetics. 132 (2): 387–402. doi:10.1093/genetics/132.2.387. ISSN 0016-6731. PMC 1205144. PMID 1427035.
A sisterchromatid refers to the identical copies (chromatids) formed by the DNA replication of a chromosome, with both copies joined together by a common...
chromosome. Chromatids may be sister or non-sisterchromatids. A sisterchromatid is either one of the two chromatids of the same chromosome joined together...
Sisterchromatid exchange (SCE) is the exchange of genetic material between two identical sisterchromatids. It was first discovered by using the Giemsa...
replicated so that it consists of two identical sisterchromatids, which remain held together through sisterchromatid cohesion. This S-phase can be referred to...
Cohesin holds sisterchromatids together after DNA replication until anaphase when removal of cohesin leads to separation of sisterchromatids. The complex...
Nondisjunction is the failure of homologous chromosomes or sisterchromatids to separate properly during cell division (mitosis/meiosis). There are three...
containing 2 sisterchromatids that developed during replication in the S phase of interphase) align themselves on the metaphase plate. Then, the sister chromatids...
originate from the same organism, they are different from sisterchromatids. Sisterchromatids result after DNA replication has occurred, and thus are identical...
of the cell. Each chromatid has its own kinetochore, and all of the microtubules that are bound to kinetochores of sisterchromatids radiate from opposite...
links a pair of sisterchromatids together during cell division. This constricted region of chromosome connects the sisterchromatids, creating a short...
the chromatids: kinetochore microtubules, interpolar microtubules, and astral microtubules. The centromeres are split, and the sisterchromatids are pulled...
same number of chromosomes) in S phase, two sisterchromatids are held together by a centromere. Each chromatid has its own kinetochore, which face in opposite...
is in a diploid state and consists of two sisterchromatids; however, the chromatin of the sisterchromatids is not yet condensed enough to be resolvable...
structure of eukaryotic cells that forms during cell division to separate sisterchromatids between daughter cells. It is referred to as the mitotic spindle during...
during sexual reproduction between two homologous chromosomes' non-sisterchromatids that results in recombinant chromosomes. It is one of the final phases...
chromosomes are long, thin, and thread-like. Each chromosome has two chromatids. The two chromatids are joined at the centromere. Gene transcription ceases during...
replication, so that each chromosome forms two copies called chromatids. These chromatids separate to opposite poles, a process facilitated by a protein...
to a bundle of microtubules and is under balanced bipolar tension. Sisterchromatids require active separase to hydrolyze the cohesin that bind them together...
structure that forms between homologous chromosomes (two pairs of sisterchromatids) during meiosis and is thought to mediate synapsis and recombination...
incidence of recombination between non-sister homologous chromatids is only about 1% of that between sisterchromatids. The discovery of mitotic recombination...
Sisterchromatid cohesion refers to the process by which sisterchromatids are paired and held together during certain phases of the cell cycle. Establishment...
enormous increase in exchange events between homologous chromosomes or sisterchromatids (the two DNA molecules that are produced by the DNA replication process);...
pairing of two homologous chromosomes. When the non-sisterchromatids intertwine, segments of chromatids with similar sequence may break apart and be exchanged...
line up along the metaphase plate (centre of the cell). Anaphase: Sisterchromatids are pulled to opposite poles of the cell. Telophase: Two new nuclear...
hydrolysing cohesin, which is the protein responsible for binding sisterchromatids during the early stage of anaphase. In humans, separin is encoded...
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