what are sister chromatids and when are they formed

Sister chromatids are two identical copies of a single chromosome that remain attached to each other by a centromere after DNA replication. They are formed during the S (synthesis) phase of interphase, before a cell enters mitosis or meiosis.

What are sister chromatids?

• Each sister chromatid is a replicated DNA molecule, so the pair carries the same genes in the same order.

• They are held together along their length by proteins (cohesion), most tightly at the centromere, until they are pulled apart in anaphase.

In other words, if you imagine a chromosome as a book, sister chromatids are like two freshly photocopied, stapled-together copies of that same book just before you hand one to each new “cell.”

When are they formed?

• Sister chromatids are created when DNA is replicated in S phase of interphase, before visible mitotic stages begin.

• They then stay paired through prophase and metaphase, and are finally separated into individual chromosomes during anaphase of mitosis and anaphase II of meiosis.

Why are they important?

• They ensure each daughter cell receives an exact copy of the genetic information during cell division.

• Their controlled separation at anaphase is key for maintaining the correct chromosome number and preventing genetic imbalances.

TL;DR: Sister chromatids are identical copies of a chromosome, formed during S phase of interphase, that stay joined until they separate at anaphase to give each new cell the same DNA.

Information gathered from public forums or data available on the internet and portrayed here.