Chapter 10Chapter 10Cell Growth & DivisionCell Growth & Division

Section 10–1Section 10–1Cell GrowthCell Growth

ObjectivesObjectives

What problems does growth cause What problems does growth cause for cells?for cells?

Limits To Cell GrowthLimits To Cell Growth

Key ConceptKey Concept::The The LargerLarger A Cell Becomes, The A Cell Becomes, The More DemandsMore Demands The Cell Places The Cell Places On Its DNA And The More On Its DNA And The More Trouble The Cell Has Moving Trouble The Cell Has Moving Enough Nutrients And Waste Enough Nutrients And Waste Across The Cell MembraneAcross The Cell Membrane

DNA OverloadDNA Overload

Extra Copies Of DNA Are Not MadeExtra Copies Of DNA Are Not Made Like A Small Town – Infrastructure Like A Small Town – Infrastructure

Needs To Grow As The Town GrowsNeeds To Grow As The Town Grows

DNA OverloadDNA Overload

Exchanging MaterialsExchanging Materials

Cell Membrane Cell Membrane (Surface Area)(Surface Area)

Nutrients EnterNutrients Enter Waste And Products LeaveWaste And Products Leave The Amounts Of Nutrients Needed The Amounts Of Nutrients Needed

And The Amount Of Waste And The Amount Of Waste ProducedProducedDepends On The Cells VolumeDepends On The Cells Volume

Ratio of Surface Area To VolumeRatio of Surface Area To Volume

As Cell Size IncreasesAs Cell Size Increases Volume Increases More Volume Increases More Rapidly Than Surface Area Rapidly Than Surface Area (cell membrane)(cell membrane)

Cell Membrane Can Not Cycle Cell Membrane Can Not Cycle Nutrients and Wastes Fast Nutrients and Wastes Fast

Enough.Enough.

Cell DivisionCell Division

Cells DivideCells Divide

Before They BecomeBefore They Become

To LargeTo LargeCell Division Is The Process By Which A Cell Division Is The Process By Which A

Cell Divides Into Two Cell Divides Into Two Daughter CellsDaughter Cells

Cell DivisionCell Division

Before A Cell DividesBefore A Cell Divides

It Replicates Its DNAIt Replicates Its DNA

So Each Cell HasSo Each Cell Has

An Exact CopyAn Exact Copy

Chapter 10Chapter 10Cell Growth & DivisionCell Growth & Division

10-2 Cell Division10-2 Cell Division

ObjectivesObjectives

What are the main events of the cell What are the main events of the cell cycle?cycle?

What are the four phases of mitosis?What are the four phases of mitosis?

ChromosomesChromosomes

Carry Genetic Information From One Carry Genetic Information From One Generation of Cell to the Next Generation of Cell to the Next Generation of CellsGeneration of Cells

Made Up Of: Made Up Of:

DNA + ProteinDNA + Protein

ChromosomesChromosomes

Every Organism Has A Every Organism Has A Specific Number Of ChromosomesOf Chromosomes

Fruit Flys = 8Fruit Flys = 8

Carrots = 18Carrots = 18

Humans = 46Humans = 46

Giraffe = 30Giraffe = 30

King Crab = 208King Crab = 208

ChromosomesChromosomes

Not Visible Except During Not Visible Except During DivisionDivision

Well Before Division They Well Before Division They DuplicateDuplicate

ChromosomesChromosomes

ChromatidsChromatids Just Before Division Chromosomes Just Before Division Chromosomes

Condense Into Compact, Visible Condense Into Compact, Visible Structures Called Structures Called ChromatidsChromatids

CentromereCentromere Each Chromosome Has Two, Identical Each Chromosome Has Two, Identical

Chromatids Connected By A Chromatids Connected By A CentromereCentromere

ChromosomesChromosomesChromatid A

Chromatid A

Copy of Chromatid A

Copy of Chromatid A

Centromere

Microtubulesor

Spindle Fibers

Kenitophore

The Cell CycleThe Cell Cycle

Key ConceptKey Concept::

During The Cell CycleDuring The Cell Cycle: : A Cell GrowsA Cell GrowsPrepares For DivisionPrepares For DivisionDivides To Form Two Divides To Form Two Daughter CellsDaughter CellsEach Daughter Cell Then Each Daughter Cell Then Begins The Cycle AgainBegins The Cycle Again

Cell CycleCell Cycle

InterphaseInterphase

Time In-Between Time In-Between Cell DivisionsCell Divisions

Cell Division Cell Division oror M phase M phase

Events Of The Cell CycleEvents Of The Cell Cycle

InterphaseInterphaseMay Be Quite LongMay Be Quite Long

Divided Into 3 PartsDivided Into 3 Parts

The 3 Parts of InterphaseThe 3 Parts of Interphase

G1 PhaseG1 Phase

Cell Grows In SizeCell Grows In Size

Synthesize New Proteins & Synthesize New Proteins & OrganellesOrganelles

The 3 Parts of InterphaseThe 3 Parts of Interphase

S PhaseS Phase

Chromosomes Are Chromosomes Are ReplicatedReplicated

Once This Phase Begins The Once This Phase Begins The Cell Completes DivisionCell Completes Division

The 3 Parts of InterphaseThe 3 Parts of Interphase

G2 PhaseG2 Phase

Organelles & Proteins Organelles & Proteins Required For Mitosis Are Required For Mitosis Are ProducedProducedCell Is Now Ready To EnterCell Is Now Ready To Enter

M Phase (Mitosis)M Phase (Mitosis)

MitosisMitosis

Key ConceptKey Concept::Biologists Divide The Events Of Biologists Divide The Events Of

Mitosis Into Mitosis Into Four Phases:Four Phases:

1.1. ProphaseProphase

2.2. MetaphaseMetaphase

3.3. AnaphaseAnaphase

4.4. TelophaseTelophase

ProphaseProphase11stst & Longest & Longest

PhasePhase Chromosomes Chromosomes

Become Become VisibleVisible

CentriolesCentrioles Separate & Separate & Take Up Take Up Position On Position On Opposite Sides Opposite Sides Of The NucleusOf The Nucleus

SpindleSpindle Begins Begins To FormTo Form

ProphaseProphaseIn AnimalsIn Animals

Spindle Fibers Spindle Fibers Attach To Attach To Centromere On Centromere On Each ChromatidEach Chromatid

In PlantsIn PlantsNo Centromere, No Centromere,

Spindle Fibers Spindle Fibers Still Form From Still Form From CentrosomesCentrosomes

Late ProphaseLate Prophase Nucleolus Nucleolus

DisappearsDisappears

Nuclear Nuclear Envelope Envelope Breaks Breaks DownDown

MetaphaseMetaphaseShortShort

Just A Few MinutesJust A Few Minutes Chromosomes Chromosomes

Line Up Across Line Up Across Center Of The CellCenter Of The Cell

Microtubules Microtubules Connect The Connect The Centromere To Centromere To The Poles Of The The Poles Of The SpindleSpindle

AnaphaseAnaphase Centromeres Centromeres

SeparateSeparate Sister Sister

Chromatids Chromatids SeparateSeparate

Each Set Of Each Set Of Chromosomes Chromosomes Pulled To Their Pulled To Their PolesPoles

TelophaseTelophase

Chromosomes Chromosomes DisperseDisperse

New Nuclear New Nuclear Envelopes FormEnvelopes Form

Spindle Breaks Spindle Breaks ApartApart

Nucleolus Nucleolus ReformsReforms

CytokinesisCytokinesis There Are Now Two There Are Now Two

Nuclei In One CellNuclei In One Cell Cytokinesis Is The Cytokinesis Is The

Division Of The Division Of The Cytoplasm Into Cytoplasm Into Two CellsTwo Cells

The Cell Membrane The Cell Membrane Is Drawn Inward Is Drawn Inward Until The Cell Until The Cell Pinches Into Two Pinches Into Two Equal PartsEqual Parts

Cytokinesis In PlantsCytokinesis In Plants

A New Cell Plate A New Cell Plate Forms In The Forms In The Middle Of The Middle Of The Cell Which Cell Which Attaches To, And Attaches To, And Becomes Part Of, Becomes Part Of, The Cell WallThe Cell Wall

Chapter 10Chapter 10Cell Growth & DivisionCell Growth & Division

Section 10-3Section 10-3

Regulating Cell GrowthRegulating Cell Growth

ObjectivesObjectives

How is the cell cycle regulated?How is the cell cycle regulated?

How are cancer cells different from How are cancer cells different from other cells?other cells?

Controls On Cell DivisionControls On Cell Division

When Cells In Cell Cultures Come In When Cells In Cell Cultures Come In Contact With Each Other, They Contact With Each Other, They Stop Growing.Stop Growing.

Why?Why?

Controls On Cell DivisionControls On Cell Division

If A Hole Is Made In The Cell Culture, If A Hole Is Made In The Cell Culture, Cell Growth Will Restart & Continue Cell Growth Will Restart & Continue Until The Hole Is Filled.Until The Hole Is Filled.

Why?Why?

Controls On Cell DivisionControls On Cell Division

In Your Body The Rate Of Cell In Your Body The Rate Of Cell Growth Is ControlledGrowth Is Controlled..

Injury Causes Rapid Division Until Injury Causes Rapid Division Until The Wound Is Healed. Then The Wound Is Healed. Then Division Slows Again. Division Slows Again.

Why?Why?

Cell Cycle RegulatorsCell Cycle Regulators

Key ConceptKey Concept::

CyclinsCyclins Regulate The Timing Of The Regulate The Timing Of The Cell Cycle In Eukaryote Cells.Cell Cycle In Eukaryote Cells.Discovered In The 1980’sDiscovered In The 1980’sCyclins Are A Family Of Closely Cyclins Are A Family Of Closely Related Proteins That Rise & Fall Related Proteins That Rise & Fall Within The Cell With The Cell CycleWithin The Cell With The Cell Cycle

Cyclins & Cell CycleCyclins & Cell Cycle

Cell Cycle RegulatorsCell Cycle RegulatorsCyclinsCyclins

When Injected When Injected Into Non-Into Non-Dividing Dividing Cells, Cyclins Cells, Cyclins Cause Mitotic Cause Mitotic Spindles To Spindles To Form.Form.

Cell Cycle RegulatorsCell Cycle RegulatorsCyclinsCyclins

When Injected When Injected Into Non-Into Non-Dividing Dividing Cells, Cyclins Cells, Cyclins Cause Mitotic Cause Mitotic Spindles To Spindles To Form.Form.

Cell Cycle RegulatorsCell Cycle RegulatorsCyclinsCyclins

When Injected Into Non-When Injected Into Non-Dividing Cells, Cyclins Cause Dividing Cells, Cyclins Cause Mitotic Spindles To Form.Mitotic Spindles To Form.

Cell Cycle RegulatorsCell Cycle Regulators

Other Regulator Proteins Other Regulator Proteins Continue To Be FoundContinue To Be Found..

Other Internal RegulatorsOther Internal Regulators

These Proteins Respond To Events These Proteins Respond To Events Inside The Cell.Inside The Cell. Several Make Sure The Cell Does Several Make Sure The Cell Does

Not Enter Mitosis Until All Not Enter Mitosis Until All Chromosomes Have Been Chromosomes Have Been Replicated.Replicated.

Others Stop The Cell From Entering Others Stop The Cell From Entering Anaphase Until All Chromosomes Anaphase Until All Chromosomes Are Attached To The Mitotic SpindleAre Attached To The Mitotic Spindle

Cyclins & Cell CycleCyclins & Cell Cycle

External RegulatorsExternal Regulators

These Respond To Events These Respond To Events Outside The CellOutside The Cell

They Direct The Cell To Speed Up They Direct The Cell To Speed Up Or Slow Down The Cell CycleOr Slow Down The Cell Cycle

These Include These Include Growth FactorsGrowth Factors

Growth FactorsGrowth Factors

Very Active DuringVery Active During Embryonic DevelopmentEmbryonic Development Wound HealingWound Healing

Other External RegulatorsOther External Regulators

Molecules On The Cell Membrane Molecules On The Cell Membrane Of Neighboring Cells Slow The Of Neighboring Cells Slow The Growth ProcessGrowth Process They are like sensors that signal They are like sensors that signal

the cell to slow/stop growththe cell to slow/stop growth

Uncontrolled Cell GrowthUncontrolled Cell Growth

Uncontrolled Cell GrowthUncontrolled Cell Growth

Key Concept:Key Concept:Cancer Cells Do Not Cancer Cells Do Not

Respond To The Respond To The Signals That Signals That Regulate The Growth Regulate The Growth Of Most Cells. As A Of Most Cells. As A Result, They Form Result, They Form Masses Of Cells Masses Of Cells Called Tumors That Called Tumors That Can Damage Can Damage Surrounding Tissue.Surrounding Tissue.

Uncontrolled Cell GrowthUncontrolled Cell Growth

MetastasisMetastasisCancer Cells Cancer Cells

Break Break Loose From Loose From The Tumor The Tumor And Invade And Invade Tissues Tissues Throughout Throughout The BodyThe Body

SmokingSmoking

RadiationRadiation

Viral InfectionViral Infection

Some Carcinogen SourcesSome Carcinogen Sources

p53 Genep53 Gene

Usually Stops The Cell Cycle Usually Stops The Cell Cycle Until Chromosomes Have Been Until Chromosomes Have Been Properly Replicated.Properly Replicated.

High Percentage Of Cancers Cells High Percentage Of Cancers Cells Have Defects At This Gene SiteHave Defects At This Gene Site