Chromosome Thickness in Different Phases of Cell Division

Anaphase:
- During anaphase, the chromosomes are the thickest.
- This is because the sister chromatids, which were held together at the centromere during metaphase, are now being pulled apart towards opposite poles of the cell.
- The thickening of the chromosomes is due to the condensation of the chromatin fibers, making them more visible under a microscope.

Metaphase:
- In metaphase, the chromosomes are also thick but not as much as in anaphase.
- This phase is characterized by the alignment of chromosomes along the metaphase plate in the center of the cell.
- The chromosomes are condensed and can be clearly observed as individual structures.

Telophase:
- During telophase, the chromosomes begin to decondense as the nuclear envelope reforms around each set of separated sister chromatids.
- The chromosomes become less thick as they start to unravel and return to their less condensed state.
- The cell prepares for cytokinesis, the final stage of cell division.

Interphase:
- In interphase, the chromosomes are the least thick as they are in their least condensed state.
- This phase is characterized by the cell carrying out its normal functions and preparing for the next round of cell division.
- The chromatin fibers are loosely packed and not clearly visible as distinct chromosomes.

In conclusion, the chromosomes are the thickest during anaphase, followed by metaphase, telophase, and interphase in decreasing order of thickness. This variation in chromosome thickness is due to the dynamic changes in chromatin condensation and decondensation that occur throughout the cell cycle.