Each Phase of Mitosis has Unique Traits That Can be Identified Under a Microscope Or in a Micrograph
1. Prophase: The Preparation Stage
The first stage of mitosis, during which chromosomes condense and the mitotic spindle begins to form.
- Chromosome Condensation: Chromatin fibers coil tightly, making chromosomes visible as distinct structures.
- Sister Chromatids: Each chromosome consists of two identical sister chromatids joined at a centromere.
- Spindle Formation: Microtubules assemble into a spindle, a structure that will guide chromosome movement.
- Nuclear Envelope Breakdown: The nuclear membrane disintegrates, allowing spindle fibers to attach to chromosomes.
To identify prophase, look for thickened chromosomes and the disappearance of the nuclear envelope.
2. Metaphase: The Alignment Stage
The second stage of mitosis, during which chromosomes align at the cell's equator.
- Chromosome Alignment: Chromosomes line up along the cell’s equator, forming the metaphase plate.
- Spindle Attachment: Spindle fibers attach to the kinetochores, protein structures on the centromeres of each chromatid.
In metaphase, look for chromosomes neatly arranged in a line at the cell’s center.
3. Anaphase: The Separation Stage
The third stage of mitosis, during which sister chromatids are pulled apart to opposite poles of the cell.
- Chromatid Separation: Cohesin proteins holding sister chromatids together are cleaved, allowing them to separate.
