in these two pictures are the interphase of the cell cycle. it represents the nucleus and the cell membrane, and when the DNA starts to replicate.
these two pictures represent the second stage, the prophase stage. These pictures represent the replicated DNA molecules joining together to form sister chromatids.
the first picture represents the metaphase stage when they line up in the middle. the second picture represents the anaphase stage when the sister chromatids separate.
the first picture represents the telophase stage. when the fibres disappear. the second picture represents the cytokinesis, when the cells divide into two.