<P> In the process of crossing - over, genes are exchanged by the breaking and union of homologous portions of the chromosomes' lengths . Structures called chiasmata are the site of the exchange . Chiasmata physically link the homologous chromosomes once crossing over occurs and throughout the process of chromosomal segregation during meiosis . Both the non-crossover and crossover types of recombination function as processes for repairing DNA damage, particularly double - strand breaks . At the diplotene stage of prophase I the synaptonemal complex disassembles before which will allow the homologous chromosomes to separate, while the sister chromatids stay associated by their centromeres . </P> <P> In metaphase I of meiosis I, the pairs of homologous chromosomes, also known as bivalents or tetrads, line up in a random order along the metaphase plate . The random orientation is another way for cells to introduce genetic variation . Meiotic spindles emanating from opposite spindle poles attach to each of the homologs (each pair of sister chromatids) at the kinetochore . </P> <P> In anaphase I of meiosis I the homologous chromosomes are pulled apart from each other . The homologs are cleaved by the enzyme separase to release the cohesin that held the homologous chromosome arms together . This allows the chiasmata to release and the homologs to move to opposite poles of the cell . The homologous chromosomes are now randomly segregated into two daughter cells that will undergo meiosis II to produce four haploid daughter germ cells . </P> <P> After the tetrads of homologous chromosomes are separated in meiosis I, the sister chromatids from each pair are separated . The two haploid (because the chromosome no. has reduced to half . Earlier two sets of chromosomes were present, but now each set exists in two different daughter cells that have arisen from the single diploid parent cell by meiosis I) daughter cells resulting from meiosis I undergo another cell division in meiosis II but without another round of chromosomal replication . The sister chromatids in the two daughter cells are pulled apart during anaphase II by nuclear spindle fibers, resulting in four haploid daughter cells . </P>

When do homologous chromosomes separate from each other during meiosis