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Cell Reproduction
Why do Cells Divide?
Section 5-1, 5-2
Why must the cell divide?
Nutrients and waste
pass through the cell
membrane
When the cell
membrane no longer
has a large enough
surface area to
transport the volume
of the cell
It divides!
How long do our cells last?
In the human body our cells last between
two weeks (a skin cell)
to 16 years (our muscles)
Cell division occurs more rapidly in embryos
and children
The Cell
Cycle
Interphase
The longest phase of the cell
cycle
• G1 phase – the growth phase, organelles
increase in number, longest phase of
interphase
• S phase – chromosomes are replicated
• G2 phase- cell continues to grow
What is a Chromosome?
Mitosis
The Division of Chromosomes
Specifically
the chromosomes
in somatic cells
Prophase
Chromosomes shorten
and thicken
Nuclear membrane
disappears
Spindle fibers form
Centrioles move to
opposite poles
Metaphase
Chromosomes
line up at
equatorial plate
Attach to spindle
fibers with
centromere
Anaphase
• Chromosomes
move towards
poles
Telophase
• Nuclear
membrane forms
around
chromosomes
Cytokinesis
The division of the cytoplasm
The cell membrane forms between the
two new identical daughter cells