Download 5.2 Mitosis and Cytokinesis

5.2 Mitosis and Cytokinesis
KEY CONCEPT
Cells divide during mitosis and cytokinesis.
5.2 Mitosis and Cytokinesis
• One long continuous thread
chromatid
of DNA coiled around
histones (proteins) is called
chromatin.
• One half of a duplicated
chromosome is a chromatid.
• Sister chromatids are held
together at the centromere.
• Telomeres protect DNA and do
not include genes.
centromere
telomere
Condensed, duplicated chromosome
5.2 Mitosis and Cytokinesis
Chromosomes condense at the start of mitosis.
• DNA wraps around proteins (histones) that condense it.
DNA double
helix
DNA and
histones
Chromatin
Supercoiled
DNA
5.2 Mitosis and Cytokinesis
B. Mitotic Phase- Mitosis and cytokinesis produce two
genetically identical daughter cells.
Parent cell
• 1.Interphase
prepares the cell to
divide.
• DNA is duplicated.
centrioles
spindle fibers
centrosome
nucleus with
DNA
5.2 Mitosis and Cytokinesis
Cell structures and mitosis
• Centrosomes-organelle that is the main microtubule
organizing center.
• Aster-cellular star shaped structure that forms around the
centrosome-made of microtubules
• Equator-mid section of the dividing cell
• Cleavage furrow - indentation that begins the formation of
the new cell membrane
• Cell plate- the new cell wall
• Kinetorchore fibers- attachment points on the centromere
where the chromosomes are held together to make an X
• Spindle- fibers that separate the chromosomes
• Microtubules-hollow, protein fibers and rods.
• Cytokinesis-division of the cytoplasm results two
daughter cells.
5.2 Mitosis and Cytokinesis
2.During prophase, chromosomes condense, nuclear
membrane, nucleus, and nucleolus disappear,
spindle fibers form, centrioles make spindle fibers
5.2 Mitosis and Cytokinesis
– 3.During metaphase- spindle fibers randomly align
sister chromatids in the middle of the cell (equator)
5.2 Mitosis and Cytokinesis
– 4.During anaphase- spindle fibers retract and pull
the sister chromatids opposite sides of the cell
(poles)
5.2 Mitosis and Cytokinesis
– 5.During telophase- chromosomes uncoil, nuclear
membrane reforms, nucleolus reforms.
5.2 Mitosis and Cytokinesis
• 6.Cytokinesis-division of the cytoplasm
– In animal cells, the
membrane pinches
closed at a point
called cleavage
furrow.
– In plant cellsvacuoles join
together and form a
cell plate.
Result-2 identical
daughter cells with
identical copies of
genetic materialDNA
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis
5.2 Mitosis and Cytokinesis