1. DNA Replication:
* Before mitosis even begins, the cell's DNA must be duplicated. This process, called DNA replication, creates an exact copy of all the genetic information in the cell.
* Each chromosome, which is a long strand of DNA, is replicated, forming two identical sister chromatids. These chromatids are held together at a point called the centromere.
2. Chromosome Condensation:
* The replicated chromosomes condense, becoming shorter and thicker. This makes them easier to move and separate during mitosis.
3. Chromosomes Align at the Equator:
* The duplicated chromosomes line up along the equator (middle) of the cell. This alignment ensures that each daughter cell receives one copy of each chromosome.
4. Sister Chromatids Separate:
* The centromeres of the chromosomes split, and the sister chromatids are pulled apart by spindle fibers. These fibers are made of microtubules, which are protein strands that attach to the chromosomes and guide their movement.
5. Formation of Two Nuclei:
* The separated chromatids move to opposite ends of the cell. Once they are at the poles, they uncoil and begin to form new nuclear envelopes. This creates two new nuclei, each containing a full set of chromosomes.
6. Cytokinesis:
* The cytoplasm of the cell divides, separating the two new nuclei into distinct daughter cells. In animal cells, this is accomplished by a cleavage furrow that pinches the cell membrane inward. In plant cells, a cell plate forms between the two new nuclei.
Why is this important?
* Mitosis ensures that each daughter cell receives a complete and identical copy of the parent cell's DNA. This is essential for maintaining the genetic integrity of the organism and for proper development and growth.
* By replicating the DNA and carefully distributing the chromosomes, mitosis allows for the creation of two new cells that are genetically identical to the original cell. This process is crucial for all multicellular organisms.
