Question

Are sister chromatids formed at the completion of the S phase?

Answer 1

Hint: At each checkpoint, a variety of things happen. The mass of the cell is tested to confirm it has doubled, DNA replication has completed, and the DNA is not damaged near the end of the second growth phase, right before the cell enters the M phase. A mitotic control point is the name given to this location.

Complete answer:
 The cell has many sister-chromatid pairs that produce a fragile mass of tangled DNA and protein after the S phase is complete. In such a situation, any attempt to separate the linked chromatids will almost likely result in DNA breakage. The large length of interphase chromosomes can be problematic; when the spindle brings the centromeres closer together, the terminals of the long chromatid arms can be seen through the cell's midline, which cleaves into sections during cytokinesis.

Yes, During the synthesis (S) phase of interphase, a complete set of sister chromatids is formed.

The identical copies (chromatids) created by the DNA replication of a chromosome are referred to as sister chromatids, and both copies are connected together by a common centromere. To put it another way, a sister chromatid is 'one-half' of the duplicated chromosome. A dyad is made up of two sister chromatids. During the synthesis (S) phase of interphase, when all of a cell's chromosomes are replicated, a complete pair of sister chromatids is formed. During mitosis or during the second division of meiosis, the two sister chromatids are divided into two distinct cells.

Sister chromatids are different from homologous chromosomes, which are the two different copies of a chromosome that diploid organisms (like humans) inherit, one from each parent. Because they are derived from the same ancestral chromosome, sister chromatids are almost similar (because they carry the same alleles, also known as variations or versions of genes). Because pieces of each sister chromatid may have been exchanged with equivalent sections of the homologous chromatids with which they are associated during meiosis, an exception occurs near the conclusion of meiosis, after crossing over has occurred. Because they come from different parents, homologous chromosomes may or may not be identical.

In certain animals, sister chromatids appear to be the preferred template for DNA repair. Sister chromatid cohesion is required for the proper distribution of genetic information among daughter cells as well as the repair of damaged chromosomes. Aneuploidy and cancer can result from flaws in this process, particularly when checkpoints fail to detect DNA damage or wrongly attached mitotic spindles fail to function properly.

Note: Anaphase follows metaphase, when the sister chromatids of each chromosome separate and travel to opposing poles of the cell. This separation is caused by the dissolution of cohesin, which held the sister chromatids together during prophase.