Transcript Chapter 10 Cell Growth & Division Section 10-3 Regulating Cell Growth

Chapter 10
Cell Growth & Division
Section 10-3
Regulating Cell Growth
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Controls On Cell Division
When Cells In Cell Cultures Come In Contact
With Each Other, They Stop Growing.
Why?
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Controls On Cell Division
If A Hole Is Made In The Cell Culture, Cell
Growth Will Restart & Continue Until The
Hole Is Filled.
Why?
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Controls On Cell Division
In Your Body The Rate Of Cell Growth Is
Controlled.
Injury Causes Rapid Division Until The
Wound Is Healed. Then Division Slows
Again.
Why?
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Cell Cycle Regulators
Key Concept:
Cyclins Regulate The Timing Of The
Cell Cycle In Eukaryote Cells.
• Discovered In The 1980’s
• Cyclins Are A Family Of Closely
Related Proteins That Rise & Fall
Within The Cell With The Cell Cycle
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Cyclins & Cell Cycle
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Cell Cycle Regulators
Cyclins
When Injected
Into NonDividing Cells,
Cyclins Cause
Mitotic Spindles
To Form.
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Cell Cycle Regulators
Cyclins
When Injected
Into NonDividing Cells,
Cyclins Cause
Mitotic Spindles
To Form.
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Cell Cycle Regulators
Cyclins
When Injected Into Non-Dividing Cells,
Cyclins Cause Mitotic Spindles To
Form.
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Cell Cycle Regulators
Other Regulator Proteins
Continue To Be Found.
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Other Internal Regulators
• These Proteins Respond To Events Inside
The Cell.
– Several Make Sure The Cell Does Not Enter
Mitosis Until All Chromosomes Have Been
Replicated.
– Others Stop The Cell From Entering
Anaphase Until All Chromosomes Are
Attached To The Mitotic Spindle
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Cyclins & Cell Cycle
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External Regulators
• These Respond To Events Outside The
Cell
• They Direct The Cell To Speed Up Or
Slow Down The Cell Cycle
• These Include Growth Factors
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Growth Factors
• Very Active During
–Embryonic Development
–Wound Healing
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Other External Regulators
• Molecules On The Cell Membrane Of
Neighboring Cells Slow The Growth
Process
– They are like sensors that signal the cell to
slow/stop growth
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Uncontrolled Cell Growth
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Uncontrolled Cell Growth
Key Concept:
Cancer Cells Do Not
Respond To The Signals
That Regulate The Growth
Of Most Cells. As A Result,
They Form Masses Of
Cells Called Tumors That
Can Damage Surrounding
Tissue.
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Uncontrolled Cell Growth
Metastasis
Cancer Cells
Break Loose
From The
Tumor And
Invade Tissues
Throughout The
Body
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Some Carcinogen Sources
Smoking
Radiation
Viral Infection
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p53 Gene
• Usually Stops The Cell Cycle Until
Chromosomes Have Been Properly
Replicated.
• High Percentage Of Cancers Cells Have
Defects At This Gene Site
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