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The Cell Cycle
Cell Reproduction
• Check this out!!
– Eukaryotic cells that grow and divide undergo an orderly
sequence of events called the cell cycle.
– The cell cycle consists of two distinct phases:
• Interphase
• Breast cancer cells dividing:
• http://www.youtube.com/watch?v=Hm0
3rCUODqg&NR=1&feature=fvwp
– Cell growth
– Sub-phases:
» G1
» S phase
» G2
• Mitotic phase
– Cell division
From One gene to 25,000 genes
– OK, we’ve talked about
how to transcribe and
translate one gene found
on the DNA in our nuclei
into a functioning protein.
But we have more than
just one gene….
– Almost all of the genes of
a eukaryotic cell
• Are located on
chromosomes in the cell
nucleus.
Eukaryotic Chromosomes
– Each eukaryotic
chromosome
contains one very
long DNA molecule,
Transcription and Translation
occur all throughout Interphase:
when the cell is growing
and duplicating all of its
cell structures and organelles!!
– Detailed representations of DNA
• Notice that the bases pair in a complementary
fashion.
• Typically bearing
thousands of genes.
– The number of
chromosomes in a
eukaryotic cell
• Depends on the
species.
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DNA Replication
– When a cell or
whole organism
reproduces, a
complete set of
genetic
instructions
must pass from
one generation
to the next.
– This happens
during S phase
Figure 10.8
The Cell Cycle
– Eukaryotic cells that grow and divide undergo an orderly sequence
of events called the cell cycle.
– The cell cycle consists of two distinct phases:
• Interphase
– Cell growth
– Sub-phases:
» G1
» S phase
» G2
Mitosis and Cytokinesis
– Mitosis
• Is the division of the chromosomes.
• Is preceded by interphase.
• Mitotic phase
– Cell division
From movie folder play:
- AnimalMitosis_SV.mpg
– Chromosomes
• Are made of chromatin, a combination of DNA
and protein molecules.
• Are not visible in a cell until cell division occurs.
– The DNA in a
cell is packed
into an
elaborate,
multilevel
system of
coiling and
folding.
2
– Before a cell
divides, it
duplicates all of
its chromosomes,
resulting in two
copies called
sister chromatids.
– When the cell
divides, the sister
chromatids
separate from
each other.
G1 phase
S phase
G2 phase
M phase
Figure 8.8.1
– Mitosis consists of four distinct phases:
•
•
•
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Prophase
Metaphase
Anaphase
Telophase
Figure 8.8.2
– Cytokinesis
• Typically occurs
during
telophase.
• Is the division of
the cytoplasm.
• Is different in
plant and animal
cells.
Figure 8.8.3
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http://www.youtube.com/watch?v=SlgV_zoHQxE&p=AC919FD76880
441F&playnext=1&index=39
Cancer Cells: Growing Out of
Control
– Normal plant and animal cells have a cell
cycle control system.
– Cancer is a disease of the cell cycle.
– Cancer cells do not respond normally to
the cell cycle control system.
Figure 8.9b
http://www.youtube.com/watch?v=Hm03rCUO
Dqg&NR=1&feature=fvwp
– Cancer cells can form tumors,
• Abnormally growing masses of body cells.
Cancer Treatment
– If a tumor is malignant,
• It can spread to other parts of the body.
– Cancer treatment can involve
• Radiation therapy, which damages DNA and disrupts
cell division.
• Chemotherapy, which uses drugs that disrupt cell
division.
• Turn and talk: How would damaging the
DNA of a cell disrupt cell division?
– Cancer
cells are
often grown
in culture
for study.
Cancer Prevention and
Survival
– Cancer prevention includes changes in lifestyle:
•
•
•
•
•
•
Not smoking
Exercising adequately
Avoiding exposure to the sun
Eating a high-fiber, low-fat diet
Visiting the doctor regularly
Performing regular self-examinations
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