Mitosis is a core mechanism of continuity in living systems: it increases cell number while preserving genetic information. In multicellular organisms it supports growth and repair, and in many species it enables efficient asexual reproduction.

Core idea: what mitosis accomplishes

Mitosis distributes duplicated chromosomes so that one parent cell produces two genetically identical daughter cells (same DNA sequence and chromosome number as the parent cell).

Diagram of the major stages of mitosis (prophase → prometaphase → metaphase → anaphase → telophase) and cytokinesis. It highlights how sister chromatids align at the metaphase plate and then separate to opposite poles, preserving chromosome number in each daughter cell. Source

This genetic consistency is what makes mitosis useful for building, maintaining, and copying bodies.

Key implications of “genetically identical”:

Condensed schematic of mitosis stages from late interphase (G2) through telophase and cytokinesis. It functions as a quick visual index of the phase names and the major visible chromosome/spindle changes across the process. Source

• Genome stability: daughter cells retain the same instructions for structure and function.

• Functional continuity: specialised tissues can be maintained because replacement cells can match required genetic programs.

• Clonal growth: groups of cells derived from one parent form a clone (genetically identical cell lineage).

Role 1: Growth in multicellular organisms

Growth requires an increase in cell number, not just cell size. Mitosis provides new cells that integrate into tissues while maintaining the organism’s genetic identity.

How mitosis supports growth

• Embryonic and juvenile growth: repeated mitotic divisions rapidly increase cell number to build tissues and organs.

• Scaling body structures: as the organism enlarges, mitosis supplies additional cells to expand structures (e.g., skin, muscle fibres via added nuclei from dividing precursor cells).

• Maintaining tissue architecture: because daughter cells are genetically identical, they can follow the same developmental instructions as surrounding cells.

Plant growth as a mitotic process

Plant growth is strongly localised:

• Meristems (regions of active mitosis) generate cells that later elongate and differentiate, increasing root and shoot length.

Micrographs showing the shoot apical meristem and root apical meristem, the primary sites of mitotic cell division in plants. The images emphasize that plant growth is concentrated in discrete regions where cells remain actively dividing before elongation and differentiation. Source

• Mitotic divisions supply “raw material” cells that can specialise into vascular tissue, epidermis, or photosynthetic mesophyll.

Role 2: Tissue repair and cell replacement

Many tissues experience wear, damage, or routine cell loss. Mitosis replaces cells to preserve tissue function and organismal survival.

Routine maintenance (high turnover tissues)

Mitosis continually replaces cells in tissues such as:

• Epithelia (skin and lining of the digestive tract), where abrasion and chemical exposure cause frequent cell loss.

• Blood-forming tissues, where mitotically active precursor cells generate new cells that mature into functional types.

Repair after injury

When tissue is damaged, local signals can stimulate nearby cells (or resident stem/progenitor cells) to divide by mitosis:

• Wound closure: new cells fill gaps and restore barriers.

• Regeneration capacity varies: some organisms and tissues replace lost parts extensively, while others form scar tissue with limited restoration of original structure.

Limits and trade-offs

• Highly specialised cells may divide rarely or not at all; repair then depends on less specialised precursor cells.

• Rapid repair prioritises restoring function, sometimes at the expense of perfectly recreating original organisation.

Role 3: Asexual reproduction

In many eukaryotes, asexual reproduction relies on mitosis to produce offspring genetically identical to the parent. This is efficient when conditions are stable and a successful genotype can be copied quickly.

Common mitosis-based strategies

• Budding: a new individual grows from the parent and detaches after mitotic growth.

• Fragmentation with regrowth: body pieces develop into complete organisms through mitotic division.

• Vegetative propagation (plants): runners, tubers, bulbs, and cuttings can develop into whole plants via mitosis, producing genetically identical offspring.

Biological consequences

• Speed and efficiency: no mate required; population size can increase rapidly.

• Low genetic variation among offspring: beneficial for maintaining a well-adapted genotype, but can reduce adaptability if environments change.