They all have 6 in its outer shell because they are all in the same group in the periodic table. Your VERY VERY welcome (:
The paternal (blue) chromosomal and the maternal (pink) chromosome are homologous chromosomes. Following chromosomal replication, the blue chromosome is composed of two identical sister chromatids and the pink chromosome is composed of two identical sister chromatids.
Crossovers occur when homologous chromosomes are. aligned: chromatids from two different chromosomes can. exchange segments as in Fig. 3. In Fig. 3a, chromatids from. two homologous chromosomes come in contact at an. equivalent point along their lengths.