the spindle fibers disappear and a new nucleus membrane forms around each set of DNA molecules
is it Prophase I?
Far from it. The disappearance of spindle fibers and the formation of nuclear membranes around the new sets of DNA occurs at the END of the process.
Out of the four major phases, which is the last to occur?
than is Chromosome pairs line up in the middle of the cell?
No, the described process of spindle fibers disappearing and new nucleus membranes forming around each set of DNA molecules does not occur in Prophase I.
To determine the correct phase, let's break down the different stages of cell division:
1. Interphase: This is the phase where the cell prepares for division by undergoing normal cell functions, growing, and duplicating its DNA.
2. Prophase: This is the first stage of mitosis, where the chromosomes become visible, condense, and the nucleolus disappears. The spindle fibers form and attach to the centromeres of the chromosomes.
3. Metaphase: The chromosomes align at the cell's equator, forming a metaphase plate. The spindle fibers attach to the centromeres and prepare to separate the chromosomes.
4. Anaphase: The spindle fibers pull the sister chromatids apart, separating them to opposite poles of the cell.
5. Telophase: The separated chromosomes reach the poles of the cell. The spindle fibers disappear, and a new nuclear membrane forms around each set of chromosomes, forming two daughter nuclei.
Based on the description provided, the process mentioned matches the events of Telophase, specifically Telophase II if it's in the context of meiosis (cell division that produces gametes). In mitosis, Telophase would refer to the final stage of the process.