Cell Division and Mitosis One parent cell giving rise to two identical daughter cells.
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Transcript of Cell Division and Mitosis One parent cell giving rise to two identical daughter cells.
Cell Division and Mitosis
One parent cell giving rise to two identical daughter cells
What is Mitosis?
Mitosis is the process of duplication of chromosomes and division of the nucleus prior to cell division.
5 Phases of Mitosis
InterphaseProphaseMetaphaseAnaphaseTelophase
Interphase
Includes the time that the cell is not actively dividing so may last a long time
The cell carries out its normal life functions during this phase
DNA is in the form of chromatin – long threadlike strands, not visible with light microscope
Late Interphase
Chromosomes have replicated.
Nuclear membrane is still intact
Nuclei stained blue; Nuclei stained blue; Center and right cell in Center and right cell in
interphaseinterphasePublic Domain: Public Domain: http://en.wikipedia.org/wiki/File:HeLa_cells_stained_with_Hoechst_33258.jpg
Interphase
= Chromatin= Chromatin
Prophase
Chromatin coils into chromatids and become easily visible with light microscope.
Duplicate chromosomes are attached at the centromeres.
Fluorescence microscope image of two
mouse cell nuclei in prophase (scale bar is 5 µm).
http://en.wikipedia.org/wiki/Prophase
Prophase
In the cell:Centrioles move to opposite ends of the
cell (animal cells)Spindle formsNucleolus disappearsNuclear membrane breaks down
Different Forms of Chromosomes
(1) Chromatin during interphase with centromere. (2) Condensed chromatin during prophase. (Two copies of the DNA molecule are now present) (3) Sister chromatids from the end of prophase through anaphase.
Image modified from Image modified from http://commons.wikimedia.org/wiki/File:Chromatin_chromosome.png
Prophase
http://en.wikipedia.org/wiki/Prophase
Chromosomal components:(1) Chromatid(2) Centromere(3) Short arm(4) Long arm
http://en.wikipedia.org/wiki/Centromere
Metaphase
The chromosomes have aligned along the equator of the cell attached to the spindle fibers by the centromeres
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Anaphase
Each centromere splits allowing identical sister chromatids to separate and move along the spindle fibers toward opposite ends of the cell.
Anaphase
Early Anaphase: The chromosomes are starting to migrate toward opposite poles.
Late Anaphase: The contraction of the spindle fibers has moved the separate masses of chromatids farther from the equator.
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Onion Root TipOnion Root Tip
Whitefish eggWhitefish egg
Anaphase
http://en.wikipedia.org/wiki/Anaphasehttp://en.wikipedia.org/wiki/Anaphase
Telophase
The chromatids have reached the poles. The chromatids uncoil back into chromatin.
Each set of chromosomes becomes incorporated in a new nucleus as the nuclear membrane reforms.
Cytokinesis or cell division now occurs.
http://en.wikipedia.org/wiki/Telophasehttp://en.wikipedia.org/wiki/Telophase
Daughter Cells in Interphase
After cytokinesis: Cells may enter a prolonged period of
interphase when all the processes that normally take place in the cell occur, except for cell division.
Cells may repeat the steps of mitosis and divide again
Phases of Mitosis – Another Look
Public Domain: http://commons.wikimedia.org/wiki/File:Interphase_and_Mitosis.svgPublic Domain: http://commons.wikimedia.org/wiki/File:Interphase_and_Mitosis.svg
Mitosis in Onion Root Tip
http://http://commons.wikimedia.org/commons.wikimedia.org/wiki/wiki/File:Onion_root_mitosis.jpgFile:Onion_root_mitosis.jpg
Can you find:Can you find:
ProphaseProphase
MetaphaseMetaphase
AnaphaseAnaphase
TelophaseTelophase
http://commons.wikimedia.org/wiki/File:Mitosis_schematic_diagram-en.svghttp://commons.wikimedia.org/wiki/File:Mitosis_schematic_diagram-en.svg