1. Interphase:
* G1 Phase: The cell grows, synthesizes proteins, and prepares for DNA replication.
* S Phase: The cell replicates its DNA. Each chromosome, initially consisting of a single chromatid, is now duplicated, forming two identical sister chromatids connected at the centromere.
* G2 Phase: The cell continues to grow and produce proteins required for mitosis.
2. Prophase:
* Chromatin Condensation: The duplicated chromosomes condense, becoming visible under a microscope.
* Spindle Formation: The mitotic spindle, made of microtubules, begins to form at the poles of the cell.
* Nuclear Envelope Breakdown: The nuclear membrane surrounding the nucleus disintegrates, allowing the spindle fibers to access the chromosomes.
3. Metaphase:
* Chromosome Alignment: The chromosomes line up at the cell's equator, called the metaphase plate, with the centromeres attached to the spindle fibers. This ensures that each daughter cell receives one copy of each chromosome.
4. Anaphase:
* Sister Chromatid Separation: The centromeres divide, separating the sister chromatids. The spindle fibers pull the chromatids apart, moving them to opposite poles of the cell.
5. Telophase:
* Nuclear Envelope Reformation: The nuclear membrane reforms around each set of chromosomes at the poles of the cell.
* Chromosomes Uncoil: The chromosomes decondense, returning to their less compact state.
* Cytokinesis: The cytoplasm divides, separating the two daughter cells. In animal cells, a cleavage furrow forms; in plant cells, a cell plate forms.
Diploidy and Genetic Identity:
* Diploidy: The original cell is diploid, meaning it has two sets of chromosomes. During interphase, each chromosome is replicated, creating two identical sister chromatids. This ensures that each daughter cell receives a complete set of chromosomes, maintaining diploidy.
* Genetic Identity: Because the chromosomes are duplicated and precisely separated during mitosis, the two daughter cells inherit identical genetic material from the parent cell. They are genetically identical clones.
In summary:
Mitosis meticulously replicates the parent cell's DNA and ensures its equal distribution to two daughter cells. The careful organization and separation of chromosomes during mitosis guarantee that both daughter cells are diploid and genetically identical to the parent cell, preserving the organism's genetic information.
