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The Cell Cycle
Biology
Section 6-2
The Cell Cycle
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Describes the life of a eukaryotic cell
The Cell Cycle – repeating sequence of
cellular growth and division during the
life of an organism
Consists of 5 stages
The Cell Cycle
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Cell spends 90% of its time in the first 3
stages of cycle, collectively called
interphase
Cell enters the last 2 stages only when
it’s time to divide
5 Stages of the Cell Cycle
1)
2)
G1 Phase (first growth phase)
- cell grows rapidly and does routine
procedures
- largest portion of cell’s life
- cells that don’t divide (nerve cells) stay in G1
phase their whole life
S Phase (synthesis phase)
- DNA copied
- at end, each chromosome consists of 2
chromatids
5 Stages of Cell Cycle
3)
4)
G2 Phase (second growth phase)
- preparation for nucleus dividing
- microtubules made – help move
chromosomes during mitosis
Mitosis
- process during cell division in which
nucleus of a cell divides into 2 nuclei
- each nucleus has the same # and kinds of
chromosomes as the original cell
5 Stages of Cell Cycle
5)
Cytokenesis
- cytoplasm divides
- mitosis and cytokenesis make new
cells that allow us to grow, repair, etc
The Cell Cycle
Cell Cycle Carefully Controlled
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Cell cycle controlled by 3 checkpoints
that determine when next stages begin