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Chapter 10 Cell Growth & Division
Section 10–1 Cell Growth
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Objectives What problems does growth cause for cells?
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Limits To Cell Growth Key Concept:
The Larger A Cell Becomes, The More Demands The Cell Places On Its DNA And The More Trouble The Cell Has Moving Enough Nutrients And Waste Across The Cell Membrane
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DNA Overload Extra Copies Of DNA Are Not Made
Like A Small Town – Infrastructure Needs To Grow As The Town Grows
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DNA Overload
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Exchanging Materials Cell Membrane (Surface Area) Nutrients Enter
Waste And Products Leave The Amounts Of Nutrients Needed And The Amount Of Waste Produced Depends On The Cells Volume
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Ratio of Surface Area To Volume
As Cell Size Increases Volume Increases More Rapidly Than Surface Area (cell membrane) Cell Membrane Can Not Cycle Nutrients and Wastes Fast Enough.
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To Large Before They Become Cell Division Cells Divide
Cell Division Is The Process By Which A Cell Divides Into Two Daughter Cells
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Before A Cell Divides It Replicates Its DNA So Each Cell Has
Cell Division Before A Cell Divides It Replicates Its DNA So Each Cell Has An Exact Copy
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Chapter 10 Cell Growth & Division
10-2 Cell Division
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Objectives What are the main events of the cell cycle?
What are the four phases of mitosis?
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Chromosomes DNA + Protein
Carry Genetic Information From One Generation of Cell to the Next Generation of Cells Made Up Of: DNA + Protein
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Chromosomes Every Organism Has A Specific Number Of Chromosomes
Fruit Flys = 8 Carrots = 18 Humans = 46 Giraffe = 30 King Crab = 208
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Chromosomes Not Visible Except During Division
Well Before Division They Duplicate
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Chromosomes Chromatids Centromere
Just Before Division Chromosomes Condense Into Compact, Visible Structures Called Chromatids Centromere Each Chromosome Has Two, Identical Chromatids Connected By A Centromere
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Chromosomes Chromatid A Copy of Chromatid A Centromere Kenitophore
Microtubules or Spindle Fibers Copy of Chromatid A Chromatid A
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The Cell Cycle Key Concept: During The Cell Cycle: A Cell Grows
Prepares For Division Divides To Form Two Daughter Cells Each Daughter Cell Then Begins The Cycle Again
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Cell Cycle
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Time In-Between Cell Divisions
Interphase Time In-Between Cell Divisions
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Cell Division or M phase
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Events Of The Cell Cycle
Interphase May Be Quite Long Divided Into 3 Parts
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The 3 Parts of Interphase
G1 Phase Cell Grows In Size Synthesize New Proteins & Organelles
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The 3 Parts of Interphase
S Phase Chromosomes Are Replicated Once This Phase Begins The Cell Completes Division
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The 3 Parts of Interphase
G2 Phase Organelles & Proteins Required For Mitosis Are Produced Cell Is Now Ready To Enter M Phase (Mitosis)
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Mitosis Key Concept: Biologists Divide The Events Of Mitosis Into Four Phases: Prophase Metaphase Anaphase Telophase
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Prophase 1st & Longest Phase Chromosomes Become Visible
Centrioles Separate & Take Up Position On Opposite Sides Of The Nucleus Spindle Begins To Form
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Prophase In Animals In Plants
Spindle Fibers Attach To Centromere On Each Chromatid In Plants No Centromere, Spindle Fibers Still Form From Centrosomes
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Late Prophase Nucleolus Disappears Nuclear Envelope Breaks Down
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Metaphase Short Just A Few Minutes
Chromosomes Line Up Across Center Of The Cell Microtubules Connect The Centromere To The Poles Of The Spindle
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Anaphase Centromeres Separate Sister Chromatids Separate
Each Set Of Chromosomes Pulled To Their Poles
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Telophase Chromosomes Disperse New Nuclear Envelopes Form
Spindle Breaks Apart Nucleolus Reforms
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Cytokinesis There Are Now Two Nuclei In One Cell
Cytokinesis Is The Division Of The Cytoplasm Into Two Cells The Cell Membrane Is Drawn Inward Until The Cell Pinches Into Two Equal Parts
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Cytokinesis In Plants A New Cell Plate Forms In The Middle Of The Cell Which Attaches To, And Becomes Part Of, The Cell Wall
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Chapter 10 Cell Growth & Division
Section 10-3 Regulating Cell Growth
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Objectives How is the cell cycle regulated?
How are cancer cells different from other cells?
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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 Non-Dividing 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 Cyclins
When Injected Into Non-Dividing Cells, Cyclins Cause Mitotic Spindles To Form.
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Other Regulator Proteins Continue To Be Found.
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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