Mitosis — Core Principles
Core Principles
Mitosis is a fundamental type of cell division where a single parent cell divides into two genetically identical daughter cells. It's a crucial process for growth, repair, and asexual reproduction in eukaryotic organisms.
The cell first prepares for division during interphase, replicating its DNA and organelles. Mitosis itself, known as the M-phase, involves two main stages: karyokinesis (nuclear division) and cytokinesis (cytoplasmic division).
Karyokinesis proceeds through four distinct phases: Prophase (chromatin condenses, nuclear envelope breaks down), Metaphase (chromosomes align at the equatorial plate), Anaphase (sister chromatids separate and move to opposite poles), and Telophase (new nuclear envelopes form around the separated chromosomes, which decondense).
Following nuclear division, cytokinesis physically divides the cytoplasm, forming two complete daughter cells. In animal cells, this occurs via a cleavage furrow, while in plant cells, a cell plate forms.
The outcome is two diploid cells, each with an identical set of chromosomes to the parent cell, ensuring genetic continuity.
Often confused with
Side-by-side differences the NEET paper likes to test.
| Aspect | Mitosis | Meiosis |
|---|---|---|
| Purpose | Growth, repair, asexual reproduction | Sexual reproduction (gamete formation) |
| Location | Somatic cells (body cells) | Germ cells (gonads) |
| Number of divisions | One nuclear division | Two nuclear divisions (Meiosis I & Meiosis II) |
| Number of daughter cells | Two | Four |
| Genetic identity of daughter cells | Genetically identical to parent cell | Genetically different from parent cell and each other |
| Chromosome number in daughter cells | Same as parent cell (e.g., 2n -> 2n) | Half of parent cell (e.g., 2n -> n) |
| Homologous chromosomes | Do not pair or undergo crossing over | Pair up (synapsis) and undergo crossing over in Prophase I |
| Sister chromatids separation | Separate in Anaphase | Separate in Anaphase II (homologous chromosomes separate in Anaphase I) |
Mitosis and meiosis are both forms of cell division, but they serve fundamentally different biological purposes and outcomes. Mitosis is a conservative process, producing two genetically identical diploid cells for growth, repair, and asexual reproduction, maintaining the chromosome number.
Meiosis, conversely, is a reductive division, yielding four genetically distinct haploid cells (gametes) essential for sexual reproduction, reducing the chromosome number by half and introducing genetic variation through crossing over.
Understanding these distinctions is critical for NEET aspirants.
Why it is tested: NEET relevance: This comparison is a high-yield topic for NEET. Questions frequently test the differences in outcomes, phases, and genetic implications of mitosis versus meiosis, often involving chromosome and DNA content changes.