The spindle fibers shorten and the centromere divides, so each chromosome becomes two separate chromatids.

缩短了，着粒分裂，所以每个染体变成两个独立的染单体。

The DNA is exactly replicated, and each chromosome now becomes two identical chromatids joined by the centromere.

DNA 被精确地复制了，每条染体现在变成了两条由着粒连接的相同染单体。

As a result, a double-stranded break on one of the chromosomes can be repaired by using the sister chromatid.

所以，一条染体上的双链断裂可利用其姐妹染单体进行修复。

That donor DNA will act like a sister chromatid as a reference to recreate the lost genetic information.

该供体DNA会像姐妹染单体一样，作为重建遗传信息的参考。

Each daughter cell now has half the number of chromosomes but each chromosome consists of a pair of chromatids.

现在每个子细胞都有一半的染体，但每个染体都由一对染单体组成。

The paired and replicated chromosomes are called bivalents or tetrads, which have two chromosomes and four chromatids, with one chromosome coming from each parent.

配对和复制的染体被称为二价体（也称为四分体），它们有两条染体和四个染单体，每个亲本都有一条染体。

In prophase 2, we see the disappearance of the nucleoli and the nuclear envelope again as well as the shortening and thickening of the chromatids.

在前期 2，我们看到核膜消失，染单体变短变厚。

So now End 1 is placed near a similar nucleotide sequence, called the homologous sequence, because it's found in the same spot on the homologous sister chromatid.

现在End 1位于一段相似核苷酸序列附近；这段序列被称为同源序列，位于同源姐妹染单体上的相同位点。

Since homology-directed repair uses a sister chromatid as a template, this is a more reliable repair mechanism than non-homologous end joining because there's no loss of nucleotides.

由于同源介导修复是以姐妹染单体为模板，这种修复机制比非同源末端连接更可靠，因为没有核苷酸丢失。

Chromatid is the word we use to describe the newly copied chromosome: the identical copies.

染单体是我们用来描述新复制的染体的词：相同的副本。