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Disruptions to Cell Cycle
EQ: What occurs when the cell cycle spins
out of control?
What if something goes
wrong in the cell cycle?
When a cell’s DNA is damaged or
changed (mutation) the cell doesn’t
grow and divide normally;
Uncontrolled cell replication
(mitosis) occurs
Cancer is the result
https://www.youtube.com/watch?v=LEpTTolebqo
Tumors
 Mass of abnormal cells
Benign tumor
abnormal cells remain at original site as a
lump
most do not cause serious problems &
can be removed by surgery
Malignant tumor
cells leave original site
lose attachment to nearby cells
carried by blood & lymph system to other tissues
start more tumors = metastasis
impair functions of organs throughout body
Traditional treatments for cancers
 Treatments target rapidly
dividing cells
high-energy radiation
kills rapidly dividing cells
chemotherapy
stop DNA replication
stop mitosis & cytokinesis
stop blood vessel growth
Stem cells
unspecialized cells
of a developing
organism (embryo)
they divide and
develop into a
variety of cell types
Image source: http://en.wikipedia.org/wiki/File:Stem_cells_diagram.png
Cell Differentiation:
when stem cells specialize
Nerve
Cells
Muscle
Cells
Blood
Cells
Skin
Cells
Stem Cells
stem cells undergo cell reproduction
(mitosis) and then differentiation to
develop into other types of body
cells and tissues
Differentiation is…
Nerve
Cells
Muscle
Cells
Skin
Cells
Blood
Cells
Stem Cells
…the process in which a stem cell divides
and the cells specialize to become a
particular type, like a skin or blood cell
Stem Cell Video Ted-Ed