Lesson #5CELL DIVISION: MITOSIS AND CYTOKINESIS
MITOSIS CELL DIVISION
MITOTIC PHASE Division of a cell into 2 identical cells, with the same amount of DNA.
1. Mitosis: division of the nucleus
2. Cytokinesis: division of the cytoplasm
2n
2n
2n
Parent cell
Daughter cells
Identical nuclei
DNA Replication◦ All DNA molecules need to be doubled o replicated in order for the cell
to be able to make 2 nuclei out of one. Each nucleus must receive the same DNA molecules.
◦ Takes place during Interphase (Phase S)
MITOSIS: Nuclear division Four main phases
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
MITOSIS1. PROPHASE◦ Chromatin condenses into structures called chromosomes ◦ Spindle forms and centrioles migrate to the poles ◦ Nuclear membrane disassembles.◦ Nucleolus disassembles.
MITOSIS2. METAPHASE◦ Chromosomes align in the metaphase plate at the equator of the
cell.◦ Centrosomes are at opposite poles.◦ Mitotic spindle fibers connect with the kinetocore
MITOSIS3. ANAPHASE◦ Chromosomes align in the center. ◦ Centrosomes are at opposite poles◦ Mitotic spindle fibers connect with the kinetocore
MITOSIS4. TELOPHASE◦ Chromatids reach the opposite poles of the cell. ◦ There is a copy of each DNA molecule in each side. ◦ Nuclear envelope and nucleolus begin to reappear.◦ Chromosomes uncoil and become less condensed.◦ Two new nuclei are formed. The is still just 1 cell, but with 2
nuclei.
CytokinesisCytoplasm divides, cell membrane surrounds each or the two daughter cells, leaving a nucleus in each side and hence allows for the completion of cell division. In animal cells: ◦ A contractile ring forms around the equator of the cell. ◦ The contractile ring shrinks at the equator of the cell, pinching the
plasma membrane inward, forming a cleavage furrow. ◦ Eventually, there are two separate cells each with its own nucleus
and surrounded by its own plasma membrane.Source: Scitable. By Nature Education
http://www.argosymedical.com/Cellular/samples/animations/Mitosis/index.html
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