MitosisMitosis

The Cell Growth & The Cell Growth & DivisionDivision

Page 1:Page 1:Limits to Cell Growth-Limits to Cell Growth- 2 main 2 main

reasons cells divide rather than reasons cells divide rather than continuing to grow indefinitely:continuing to grow indefinitely:

–More Demands on DNA-More Demands on DNA-When cell increases in size it does When cell increases in size it does not make extra copies of DNAnot make extra copies of DNA

If cell grew without limits If cell grew without limits “information crisis” would occur.“information crisis” would occur.

Page 1 continuePage 1 continue–Exchanging Materials-Exchanging Materials-

Food, oxygen, & water have to Food, oxygen, & water have to enter the cell through the cell enter the cell through the cell membranemembrane

Waste products have to leave Waste products have to leave The rate at which this exchange The rate at which this exchange takes place depends on the takes place depends on the surface area of the cell (total surface area of the cell (total area of the cell membrane)area of the cell membrane)

Page 1 continuePage 1 continue Ratio of Surface Area to VolumeRatio of Surface Area to Volume

– Volume increases more rapidly than the surface areaVolume increases more rapidly than the surface area– Therefore, ratio of surface area to volume decreasesTherefore, ratio of surface area to volume decreases

This decrease causes serious problems for the This decrease causes serious problems for the cellcell– If too large becomes to difficult to get enough If too large becomes to difficult to get enough

oxygen and nutrients in and wastes outoxygen and nutrients in and wastes out

This is why cells do not grow much bigger even if This is why cells do not grow much bigger even if the organism of which they are a part of does.the organism of which they are a part of does.

Quick Lab (p. 242) Analyze & conclude 1-2Quick Lab (p. 242) Analyze & conclude 1-2

Page 2Page 2 Define from the chapter:Define from the chapter:1.1. Cell DivisionCell Division2.2. MitosisMitosis3.3. ChromosomeChromosome4.4. ChromatidChromatid Draw a picture of chromosome & ChromatidDraw a picture of chromosome & Chromatid5.5. Centromere Centromere6.6. Cell cycle Cell cycle7.7. Spindle fibers Spindle fibers8.8. Centrioles Centrioles Draw a picture of Centrioles & Spindle fibersDraw a picture of Centrioles & Spindle fibers

Page 3Page 3 Cell GrowthCell Growth

Describe:Describe: G1G1- - period of activity in which period of activity in which

cells do most of their growing. Cells cells do most of their growing. Cells increase in size and synthesize new increase in size and synthesize new proteins and organellesproteins and organelles

SS- Chromosomes are replicated and - Chromosomes are replicated and synthesis of DNA molecules takes synthesis of DNA molecules takes placeplace

G2-G2- Many organelles and Many organelles and molecules required for cell divisions molecules required for cell divisions are producedare produced

M phase-M phase- Mitosis MitosisAAddd d CCoolloorr!!

– InterphaseInterphase G1 phase (gap) G1 phase (gap)

growth & metabolic growth & metabolic activityactivity

S phase (DNA S phase (DNA replication)replication)

G2 phase (gapG2 phase (gap) cells ) cells prepares for divisionprepares for division

– MitosisMitosis– Cytokinesis Cytokinesis

(cytoplasmic (cytoplasmic division)division)

Page 4Page 4

Draw, label, & describe the Draw, label, & describe the phases of:phases of:

Interphase Interphase ProphaseProphase

AAddd d CCoolloorr!!

Page 5Page 5

Draw, label, & describe the phases Draw, label, & describe the phases of:of:

MetaphaseMetaphase AnaphaseAnaphase

AAddd d CCoolloorr!!

Page 6Page 6

Draw, label, & describe the phases of:Draw, label, & describe the phases of:

– TelophaseTelophase– Cytokinesis-Cytokinesis- for both plant & for both plant &

animalanimal

AAddd d CCoolloorr!!

A Cell’s Appearance A Cell’s Appearance During InterphaseDuring Interphase

Plasma membrane

Nuclear envelope

Nucleoplasm

Cytoplasm

ProphaseProphase Replicated chromosomes, Replicated chromosomes,

which are being held which are being held together by a centromere, together by a centromere, condense.condense.

Centrioles move to Centrioles move to opposite poles of the cell.opposite poles of the cell.

Nuclear envelope and Nuclear envelope and nucleolus disperse.nucleolus disperse.

Microtubules are Microtubules are assembled from tubulin assembled from tubulin proteins in the cytoplasm, proteins in the cytoplasm, and these structures and these structures associate with the associate with the centrioles and the centrioles and the chromosomes.chromosomes.

A spindle-shaped array of A spindle-shaped array of microtubules (spindle microtubules (spindle fibers) forms between the fibers) forms between the centrioles as they move centrioles as they move apart.apart.

MetaphaseMetaphase

The doubled The doubled chromosomes chromosomes become become attached to the attached to the spindle fibers by spindle fibers by their their centromeres.centromeres.

The The chromosomes chromosomes begin to line up begin to line up on the midlineon the midline

AnaphaseAnaphase The centromers The centromers

split apart and split apart and chromatid pairs chromatid pairs from each from each chromosome chromosome separate from separate from each othereach other

The chromatids The chromatids are pulled apart are pulled apart by the shortening by the shortening of the of the microtubules in microtubules in the spindle fibers.the spindle fibers.

TelophaseTelophase The chromatids The chromatids

reach the reach the opposite poles of opposite poles of the cell.the cell.

The spindle The spindle breaks down, the breaks down, the nucleolus nucleolus reappears, & a reappears, & a new nuclear new nuclear envelope forms envelope forms around each set around each set of chromosomes.of chromosomes.

A new double A new double membrane begins membrane begins to form between to form between the 2 new nuclei.the 2 new nuclei.

CytokinesisCytokinesis Animal CellsAnimal Cells- the plasma - the plasma

membrane pinches in along membrane pinches in along the equator and 2 new cells the equator and 2 new cells are separated.are separated.

Plant CellsPlant Cells- Have a rigid cell - Have a rigid cell wall, so the plasma wall, so the plasma membrane does not pinch in.membrane does not pinch in.

The cell plate is laid down The cell plate is laid down across the cell equator.across the cell equator.

A cell membrane forms A cell membrane forms around each cell, & new cell around each cell, & new cell calls form on each side of the calls form on each side of the cell plate until separation is cell plate until separation is complete.complete.

Mitosis Animation

Mitosis Animation

Now, Now, name name and and then then order order these these phasephases of s of

mitosimitosis.s.

A B C

D E F

G H I

Page 7Page 7Regulating the Cell CycleRegulating the Cell Cycle::

Cell cycle regulators-Cell cycle regulators-– early 1980’s biologists found a protein early 1980’s biologists found a protein

that increased & decreased the time with that increased & decreased the time with the cell cyclethe cell cycle

– They called it They called it cyclincyclin because it seemed to because it seemed to regulate the timing of the cell cycleregulate the timing of the cell cycle

– Since, they have discovered a whole Since, they have discovered a whole family of cyclin proteinsfamily of cyclin proteins

Page 7 ContinuedPage 7 ContinuedTwo types of Regulator ProteinsTwo types of Regulator Proteins

1.1. Internal Regulators- proteins that respond Internal Regulators- proteins that respond to events inside the cellto events inside the cell

– Allows cell cycle to proceed only when certain Allows cell cycle to proceed only when certain processes have occurred inside the cellprocesses have occurred inside the cell

– Ex: doesn’t let the cell enter mitosis until all Ex: doesn’t let the cell enter mitosis until all chromosomes have been replicatedchromosomes have been replicated

2.2. External Regulators- Proteins respond to External Regulators- Proteins respond to events outside the cellevents outside the cell

– Direct cells to speed up or slow down cellDirect cells to speed up or slow down cell– Ex: Growth factors- stimulate growth & cycle Ex: Growth factors- stimulate growth & cycle

division of cells. Important in embryonic cells & division of cells. Important in embryonic cells & wound healingwound healing

Page 8Page 8Uncontrolled Cell GrowthUncontrolled Cell Growth

CancerCancer- disorder in which some of the - disorder in which some of the body’s own cells lose the ability to body’s own cells lose the ability to control growth.control growth.

Cancer cells do not respond to the Cancer cells do not respond to the signals that regulate the growth of signals that regulate the growth of most cells, they divide uncontrollably most cells, they divide uncontrollably & & form masses of cells called tumorsform masses of cells called tumors that can damage surrounding tissue.that can damage surrounding tissue.

Page 8 ContinuedPage 8 ContinuedTwo types of tumors:Two types of tumors:1.1. Benign- Benign- does not spread to does not spread to

surrounding tissue (non cancerous)surrounding tissue (non cancerous)2.2. Malignant- Malignant- Spreads & destroys Spreads & destroys

healthy tissue (cancerous)healthy tissue (cancerous)Causes:Causes:1.1. Biological Agent- virusesBiological Agent- viruses2.2. Chemical Agent- carcinogens- Chemical Agent- carcinogens-

tobaccotobacco3.3. Physical Agent- radiationPhysical Agent- radiation4.4. GeneticsGenetics

Page 8 ContinuedPage 8 ContinuedTreatments:Treatments:

1.1. SurgerySurgery

2.2. RadiationRadiation

3.3. ChemotherapyChemotherapy

The EndThe End

Onion Root TipOnion Root Tip

Under Low Power…Under Low Power…

Look for this 1Look for this 1stst then then SWITCH TO HIGH SWITCH TO HIGH POWER!!!!!POWER!!!!!

Onion Root TipOnion Root Tip

Identify the Identify the stagesstages

Onion Root TipOnion Root Tip

Page 9Page 9

DNA Scientists Chart DNA Scientists Chart

Pg. 10Pg. 10

DNA NOTESDNA NOTES

Pg. 11Pg. 11

DNA REPLICATIONDNA REPLICATION