Cell Reproduction
Chapter 4
Cell Growth and Division
Chapter 4-1
Cells undergo division to:
Increase in number
 Repair worn out cells
 Replace cells that have died

Cell cycle
Interphase – most of the
life of any cell

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period of growth and
development
DNA replication
growth and preparation for
mitosis
Nerve and muscle cells
don’t divide remain in
interphase
Skin cells constantly change
Mitosis
The process in which
the nucleus divides to
form two identical
nuclei.
It is a series of phases
or steps.
Animal Mitosis
Interphase –

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Nucleus can be seen
DNA is replicating

(making exact copies)
Prophase –
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Chromosomes visible
Nucleolus and nuclear
membrane fade
Centrioles move to
opposite end of cell
Spindle fibers begin to
stretch across the cell
Metaphase

Double strands of
chromosomes line up
across the center of cell
Attach to a spindle
Centromere – place
where double stranded
chromosomes are held
together
Anaphase
Anaphase

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Centromeres divide
Two strands separate
Separate strands move
away toward opposite
ends of cell
Telophase


Centrioles and spindles
disappear
Chromosomes stretch
out and become harder
to see


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Nuclear membrane
forms around each
mass of chromosomes
New nucleolus appears
Cell begins to split by
pinching at cell
membrane
Daughter cells – new
cells that divided from
a parent cell
Interphase
Mitosis
Mitosis in Plant Cells
All phases are the
same as animal cells
Telophase

Cell wall is produced
to separate the cells.
http://www.biology
.arizona.edu/cell_bi
o/activities/cell_cyc
le/cell_cycle.html
Identify each phase of mitosis
below.
Identify animal mitosis
Results of Mitosis
Two Important results of mitosis:
Nucleus was divided
 Two new nuclei are identical

Cytokinesis
The period of the cell cycle when the cell
separates into two daughter cells
Animal cell cytokinesis – cell membrane pinches
in the middle and a new membrane is formed
Plant cell cytokinesis – cell wall is formed
between the two daughter cells, then a cell
membrane forms and completely separates.
.