Issues of MitosisIssues of Mitosis

““The Life and Times of the The Life and Times of the Cell”Cell”

Summary of Summary of MitosisProphase: Prophase:

Replicated chromatin condense into chromatid pairReplicated chromatin condense into chromatid pairCentrioles move to opposite polesCentrioles move to opposite polesNuclear envelope disappearsNuclear envelope disappearsSpindle fibers start to formSpindle fibers start to form

MetaphaseMetaphaseChromatid pairs line up at the equatorChromatid pairs line up at the equator

AnaphaseAnaphaseChromatid pairs splitChromatid pairs splitChromosomes are pulled to opposite poles by the spindle fibersChromosomes are pulled to opposite poles by the spindle fibers

TelophaseTelophaseChromosomes de-condense into chromatinChromosomes de-condense into chromatinNuclear envelope reappearsNuclear envelope reappearsCytoplasm is divided into 2 cells Cytoplasm is divided into 2 cells Cytokenesis Cytokenesis

One more Phase – GAP 0 (G0)One more Phase – GAP 0 (G0)

Some cells do not Some cells do not replicate their centrioles replicate their centrioles during Prophase.during Prophase.

They lose their ability to They lose their ability to dividedivide

They enter the Gap 0 They enter the Gap 0 stage stage

Neurons of the Spinal Neurons of the Spinal cord / Brain cellscord / Brain cells

Mitosis in Plant vs. Animal CellsMitosis in Plant vs. Animal CellsThe Rivalry ContinuesThe Rivalry Continues

Plants have no Plants have no centrioles but still centrioles but still form spindle form spindle fibersfibers

Plant cells divide Plant cells divide from the inside from the inside outout

Cell PlateCell Plate

““Messy Messy Metaphase”Metaphase”

Importance of MitosisImportance of Mitosis

Method of reproduction for Method of reproduction for all single celled all single celled organismsorganisms

Allows us to regenerate Allows us to regenerate cells (tissue) repair cuts, cells (tissue) repair cuts, bone breaks, etcbone breaks, etc

Growth – one cell to trillionsGrowth – one cell to trillions

How Long does the Cell Cycle How Long does the Cell Cycle Last?Last?

Pick up a textbook and turn to page 249.Pick up a textbook and turn to page 249.

Read the section titled “Life Spans of Read the section titled “Life Spans of Cells” and answer the 4 questions that Cells” and answer the 4 questions that follow.follow.

Meiosis

Special cell division Special cell division that produces Haploid that produces Haploid sex cellssex cells

Consists of one Consists of one replication and two replication and two cell divisionscell divisions

Sexual vs. AsexualSexual vs. Asexual

Asexual ReproductionAsexual Reproduction

Reproduction that doesn't Reproduction that doesn't involve sex cellsinvolve sex cells

Produces ‘clones’ of Produces ‘clones’ of previous cellsprevious cells

Ex: 1. Binary FissionEx: 1. Binary Fission

2. Fragmentation2. Fragmentation

3. Budding 3. Budding

Sexual ReproductionSexual Reproduction

Reproduction involving Reproduction involving sex cellssex cells

Produces genetically Produces genetically different offspringdifferent offspring

Sperm + egg = ZygoteSperm + egg = Zygote

(n) + (n) = (2n) (n) + (n) = (2n)

CancerA disease of uncontrolled cell divisionA disease of uncontrolled cell divisionStarts with a single cell that loses its control Starts with a single cell that loses its control

mechanisms due to a genetic mutation (mistakes in mechanisms due to a genetic mutation (mistakes in DNA replication)DNA replication)

Can be caused naturally or by carcinogens (i.e.: Can be caused naturally or by carcinogens (i.e.: tobacco smoke, chemicals, etc.)tobacco smoke, chemicals, etc.)That cell starts dividing without limit, possibly killing That cell starts dividing without limit, possibly killing the host (without treatment)the host (without treatment)

Cancer TreatmentCancer Treatment

Three basic treatments: Three basic treatments: – Surgery to remove cancerSurgery to remove cancer– Radiation to kill affected cellsRadiation to kill affected cells– New drugs are becoming available (Chemotherapy)New drugs are becoming available (Chemotherapy)

It is hard to remove cancer (tumors often lack clear boundaries)It is hard to remove cancer (tumors often lack clear boundaries)– Some tumors are very small and are found throughout the body (advanced Some tumors are very small and are found throughout the body (advanced

stages) stages)

Radiation and chemotherapy are aimed at killing cancer cellsRadiation and chemotherapy are aimed at killing cancer cells– The body then has to replace those dead cells which requires a lot of energyThe body then has to replace those dead cells which requires a lot of energy– Therefore treatment must be balanced with overall patient healthTherefore treatment must be balanced with overall patient health

Unfortunately due to natural selection cancer that seems to have Unfortunately due to natural selection cancer that seems to have disappeared can come back in the future in a form that is resistant disappeared can come back in the future in a form that is resistant to the radiation / chemotherapyto the radiation / chemotherapyUsing multiple drugs can decrease the risk of relapseUsing multiple drugs can decrease the risk of relapse– Multiple drugs decrease the probability of cells acquiring immunityMultiple drugs decrease the probability of cells acquiring immunity

Types of CancerTypes of Cancer

Lung CancerLung CancerBreast CancerBrain CancerBrain CancerSkin CancerSkin CancerOvarian CancerOvarian CancerUterine CancerUterine CancerCervical CancerCervical CancerTesticular CancerTesticular CancerKidney CancerKidney Cancer

Prostate CancerProstate CancerLeukemiaLeukemiaEye CancerEye CancerLymphatic CancerLymphatic CancerMouth CancerMouth CancerColon CancerColon CancerPancreatic CancerPancreatic CancerBone CancerBone CancerPenile CancerPenile Cancer

The cure is out there !The cure is out there !