Mitosis

What is mitosis?

Cell division, which creates two "identical" cells from a single cell
Mitosis is technically the division of the nucleus, but the cell's cytoplasm and organelles also divide during a process called cytokinesis

Karyokinesis

- Splitting of just the genetic material; chromosomes replicated in interphase and then divided

Cytokinesis

- Splitting of cell's cytoplasm and organelles

http://upload.wikimedia.org/wikipedia/commons/thumb/e/e0/Major_events_in_mitosis.svg/800px-Major_events_in_mitosis.svg.png

Why is mitosis important?

Creates identical offspring cells with equal amounts of DNA
Increases size of organism!
Mitosis is growth and repair

Where does mitosis occur?

For plants, mitosis occurs mostly in meristems (e.g. apical meristems, vascular cambium)

Mitotic Stages:

Prophase: nucleus dissolves; chromosomes exposed
Metaphase: chromosomes line up
Anaphase: chromosomes pulled apart
Telophase: new cell wall forms

Prophase

Chromosomes continue to condense
Nuclear envelope and nucleolus disassociate
e.g. 2 chromosomes & 4 chromatids

Metaphase

Centrioles organize the spindle fibers which become visible
Chromosomes aligned at equator
e.g. 2 chromosomes & 4 chromatids

Anaphase

Chromatids migrate to opposite ends of cell
e.g. 4 chromosomes & 4 chromatids

Telophase

Early Telophase

Cell plate begins to form
New nuclear envelope begins to form
e.g. 4 chromosomes & 4 chromatids

Late Telophase

Separate into 2 cells: cytokinesis
e.g. 2 chromosomes & 2 chromatids

Above: mitotic cells in the onion (Allium) root tip

Additional Resources

Scientists discover a simple set of rules that may explain how the tissues stay organized (Phys.org 15Jul2025)

└Boman et al. (2025) Dynamic Organization of Cells in Colonic Epithelium is Encoded by Five Biological Rules

A molecular switch packs DNA on time for cell division (Phys.org 9Jul2025)

└Borsellini et al. (2025) Condensin II activation by M18BP1

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