What phase of the cell cycle involves chromatin condensation and visibility of chromosomes under a microscope?

The phase of the cell cycle that involves chromatin condensation and makes chromosomes visible under a microscope is prophase. During prophase, the chromatin—a complex of DNA and proteins that is present in a loosely packed form during interphase—begins to condense into distinct chromosomes. This condensation is essential because it allows the chromosomes to be separated more easily later in the cell division process.

As prophase progresses, the nuclear envelope starts to break down, and the mitotic spindle begins to form, further facilitating the movement of chromosomes. Each chromosome consists of two sister chromatids connected at a region called the centromere. The condensation of chromatin into visible chromosomes is a critical step that marks the transition from the interphase state of DNA to the organized and segregated state necessary for mitosis.

In contrast, during other phases such as anaphase, telophase, and metaphase, chromosomes are already visible, but it is during prophase that the initial condensation occurs. Therefore, prophase is the correct answer to the question regarding when chromatin condensation and visibility of chromosomes take place.