1. Interphase: This is the "preparation" phase where the cell grows, duplicates its organelles (like mitochondria and ribosomes), and replicates its DNA.
2. Prophase:
* The duplicated DNA condenses into visible chromosomes, each consisting of two identical sister chromatids held together at the centromere.
* The nuclear envelope begins to break down.
* The spindle fibers, made of microtubules, start to form.
3. Metaphase:
* The chromosomes align at the center of the cell, called the metaphase plate, with the spindle fibers attached to the centromeres.
4. Anaphase:
* The sister chromatids separate, pulled apart by the shortening spindle fibers.
* The chromosomes move towards opposite poles of the cell.
5. Telophase:
* The chromosomes reach the poles and start to uncoil.
* The nuclear envelope reforms around each set of chromosomes.
* The spindle fibers disappear.
6. Cytokinesis:
* The cytoplasm divides, forming two separate daughter cells, each with a complete set of chromosomes and organelles.
Why are the new cells exact copies?
* DNA Replication: The DNA is replicated precisely, ensuring that both daughter cells receive an identical copy of the genetic material.
* Chromosomes: The chromosomes are perfectly duplicated and then separated equally during mitosis, ensuring both daughter cells receive a complete set of genetic instructions.
Consequences of Errors in Mitosis:
While mitosis is a highly accurate process, errors can sometimes occur. These errors can lead to:
* Mutations: Changes in the DNA sequence can lead to genetic diseases or cancer.
* Abnormal cell division: This can lead to developmental problems or uncontrolled cell growth, such as in cancer.
In summary:
Mitosis is a carefully regulated process that allows organisms to grow, repair tissues, and reproduce asexually. By accurately replicating DNA and distributing chromosomes equally, mitosis ensures that new cells are exact copies of the original cell, preserving the genetic information.
