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.
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