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Cell Division
Section 8-2
Objectives
Describe the events of binary
fission
Describe each phase of the cell
cycle
Summarize the phases of
mitosis
Objectives
Compare cytokinesis in
animal cells with cytokinesis
in plant cells
Cell Division
Process by which cells
produce offspring cells
Chromosomes
Cell Division
Cell Division in Prokaryotes
Binary fission
– Cell divides into two identical cells
– Page 148, Figure 8-4
– DNA is copied, cell grows, cell
divides, two new cells - identical to
the original
– Ex. Bacteria
Cell Division in Eukaryotes
Cytoplasm and nucleus divide
Mitosis
– Identical to original cell
Meiosis
– Reduces the number of chromosomes
by half
– Variation among cells
Cell Cycle
Life cycle of the cell
– Interphase - time between cell
divisions
– Mitosis - cell division
Interphase
Three phases
– G1 phase - cell growth
– S phase - DNA is copied
– G2 phase - growth and
preparation for cell division
Page 149, fig. 8-5
Interphase
Beginning of Interphase
– DNA is known as chromatin
– thread like material
Later Interphase
– Chromatin forms chromosomes
– Chromosomes duplicate
Interphase
Plant Cell
Animal Cell
Mitosis
Division of the nucleus
– Four phases: prophase,
metaphase, anaphase, telophase
Takes place in somatic cells
– Body cells (not sex cells)
Prophase
Begins actual cell division
Nuclear membrane disappears
Spindle and Aster form
Prophase
Plant Cell
Animal Cell
Metaphase
Chromosomes line up in the
middle of the cell
Karyotypes are made from
cells in metaphase
Metaphase
Metaphase
Plant Cell
Animal Cell
Anaphase
Chromosomes separate
Chromatids travel to opposite
poles
Anaphase
Plant Cell
Animal Cell
Telophase
Reverse of Prophase
– Chromosomes begin to disappear
– Nuclear membrane reforms
Telophase
Plant Cell
Animal Cell
Cytokinesis
Cytoplasm divides
Cleavage furrow (animal cells)
– Cell membrane pinches in at the
center of the dividing cell
In plant cells - cell plate forms