Step 1: Duplication: Just before division, every chromosome in the nucleus copies itself exactly. This results in the formation of chromatids joined together, visible under a microscope during division.
Step 2: Alignment: The duplicated chromosomes line up along the center (equator) of the cell. This alignment is critical for ensuring equal distribution of genetic material.
Step 3: Separation: Specialized cell fibers attach to the chromosomes and pull the identical copies apart toward opposite poles of the cell. Each side now contains a full set of chromosomes.
Step 4: Division: The cell membrane pinches inward, dividing the cytoplasm into two. This results in two separate cells, each with an identical nucleus containing the original diploid set of DNA.
Cell Type: Mitosis occurs in somatic cells (body cells), whereas meiosis is restricted to the production of gametes (sex cells) in reproductive organs.
Genetic Outcome: Mitosis produces genetically identical cells, while meiosis creates genetic variation through the shuffling of alleles.
| Feature | Mitosis | Meiosis |
|---|---|---|
| Purpose | Growth and Repair | Gamete Production |
| Cell Count | 2 Daughter Cells | 4 Daughter Cells |
| Genetic Info | Identical to Parent | Different from Parent |
| Chromosome No. | Diploid () | Haploid () |
Growth: Mitosis allows a single-celled zygote to develop into a complex multicellular embryo and eventually an adult by continuously producing new identical cells.
Tissue Repair: When cells are damaged or die (such as skin or red blood cells), mitosis generates replacements to restore tissue integrity and function.
Asexual Reproduction: In many organisms, mitosis is the method used to produce offspring. Because the division is mitotic, the offspring are clones of the parent, maintaining successful genetic traits.
Keyword Precision: When describing mitosis, always use the phrase "genetically identical cells." Examiners look for this specific terminology to award marks.
Chromosome Counts: Remember that mitosis preserves the chromosome number (). If a question states a parent cell has 46 chromosomes, the mitotic daughters MUST also have 46.
Identifying Context: If a scenario describes the healing of a wound or the growth of a root tip, immediately associate it with mitosis. Conversely, anything involving fertilization or sex cells is likely related to meiosis.
The Gamete Trap: A common mistake is assuming all cell division produces sex cells. Remember that mitosis NEVER produces gametes; its sole purpose is maintaining identical body cells.
Timing of Duplication: Students often forget that DNA duplication happens before the visible stages of mitosis begin. Without duplication, mitosis cannot occur correctly.
Haploid vs. Diploid: Do not confuse the terms; mitosis results in diploid cells. If you see "haploid" in an answer choice regarding mitosis, it is almost certainly a distractor.
