During metaphase, chromosomes align at the equatorial plate of the cell. The spindle fibres attach to the centromeres of each chromosome, ensuring that sister chromatids are positioned ready for separation. This stage is critical for ensuring each daughter cell receives an identical set of genetic material.
- Chromosomes line up at the cell equator in a single row.
- Spindle fibres from opposite poles attach to each centromere.
- The cell checks that all chromosomes are correctly attached before proceeding.
Anaphase
Anaphase begins when the centromeres divide and sister chromatids are pulled apart toward opposite poles of the cell. Motor proteins within the spindle fibres generate the force required to shorten the fibres and move chromatids. This is one of the shortest stages of mitosis but essential for equal distribution of DNA.
- Sister chromatids separate and move to opposite poles.
- Spindle fibres shorten, drawing chromosomes apart.
- Chromosome number remains the same until cytokinesis completes.
Telophase
In telophase, chromosomes arrive at the poles and begin to decondense. Nuclear envelopes re-form around each set of chromosomes, producing two distinct nuclei within the same cell. The spindle apparatus disassembles and the cell prepares for the final stage of division.
Cytokinesis
Cytokinesis is the physical separation of the cytoplasm into two daughter cells. In animal cells, a contractile ring of actin filaments pinches the cell membrane inward. In plant cells, a cell plate forms along the equator, eventually developing into a new cell wall between the two daughter cells.
- Animal cells divide by cleavage furrow formation.
- Plant cells divide by cell plate formation.
- Each daughter cell enters interphase with a complete set of chromosomes.
Summary
Mitosis produces two genetically identical daughter cells from a single parent cell. The process is tightly regulated by checkpoints at each stage to prevent errors in chromosome segregation. Understanding mitosis is fundamental to topics including growth, tissue repair, and the development of cancer therapies.
