Mitosis part 1 revised
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Cells need to divide through the process of mitosis in order to repair and replace damaged or dead cells, to grow and develop, and for sexual reproduction. Mitosis involves the replication of DNA and the division of the cell into two identical daughter cells. The cell cycle is tightly regulated by internal and external factors to ensure proper cell division, growth and function. Deregulation of the cell cycle controls can lead to cancer if cells divide uncontrollably and form tumors that may metastasize and spread to other parts of the body. Treatments for cancer include surgery, chemotherapy, and radiation therapy.
Mitosis part 1 revised
- 1. MitosisWhy do cells need to divide?
- 3. Recap…Cell theory…Cells are the basic structural unit of lifeCells are the functional units of lifeCells come from pre-existing cells
- 4. OverviewWhy do cells need to divide?Repair, growth, developmentTypes of reproductionSexualGenetically different2 parentsTakes time to develop, better chance of survival asexualGenetically identicalOne parentMany offspring very quickly
- 5. DNABlueprint of life, nucleic acidChromatinGranular genetic material, spread out in nucleus of non-dividing cellsChromosomesCondensed genetic material, in dividing cellsSister chromatidsIdentical copies of Chromosomes joined by a centromere (“centro-” middle)
- 8. Humans46 chromosomes 46 sister chromatidsOne from your mom, one from your dad
- 9. Cell Cycle: Life of a Cell
- 10. Cell CycleInterphase90 % of cell’s life, non dividingG1 phaseGrows, makes organellesS phaseDNA Synthesis…DNA replicatesG2 phaseCell prepares to divide, makes sure it has all important organelles for divisionM phaseWhen the cytoplasm and nucleus of the cell divides
- 11. Cell CycleThere are check points in G1, S, and G2Make sure cell is ready to move onto the next phase (has all necessary organelles, copied DNA, etc.)Once the cell has past the G1 checkpoint, it will complete the cell cycleSome cells stay in the G1 phase all their life (muscle cell, brain cells)
- 12. Regulators of Cell CycleCyclinsProtein that regulates the timing of the cell cycle in eukaryotic cellsLevels of cyclins rise and fall throughout the cell cycleCyclin-dependent Kinases (cdks)Enzymes that are activated when they bind with cyclin and they make the cell cycle continue
- 14. RegulatorsInternalFactors within the cell that control cell cycleCyclin and CDKsFamily of proteinsAllow cell cycle to proceed only when certain processes have occurredReplication of chromosomesChromosome Attachment to spindle before anaphase ExternalFactors Outside the cellGrowth factorsmolecules that bind to cell surface that signal cell to divideSimilar cells have molecules that have opposite effect so that when it becomes to crowded, cells stop dividing
- 19. M-phaseConsists of mitosis and cytokinesisMitosisProcess by which the nucleus of a cell dividesOne parent cell makes two identical daughter cellsThis is how organisms repair tissue and grow and developCytokinesis-division of the cytoplasm
- 20. Depending on cell type…Mitosis can take a few minutes or a few daysMuscle cells (non-dividing)Nerve cells (non-dividing)Skin cells (divide all the time)Digestive Tract cells (divide all the time)
- 21. Life Span of Some Human Cells
- 22. Easy way to remember M-PhasePMAT Pilates Make Annie TonedPractice Makes Athletes TrainProphaseMetaphaseAnaphaseTelophase
- 23. Prophase50-60% of timeChromosomes become visibleCentrioles develop in cytoplasm near nuclear envelopeCentrioles separate and migrate to opposite ends of nuc. Env.CentrosomeRegion where Centrioles are foundOrganize the “spindle”Fan like microtubule structure that helps separate chromosomesPlants do NOT have Centrioles
- 26. End of prophaseChromosomes coil together tightlyNucleolus disappearsNuclear envelope breaks down
- 27. MetaphaseFew minutesChromosomes line up in middle (M in metaphase MIDDLE)Microtubules connect centromere of each chromosome to the 2 poles of spindle
- 31. AnaphaseCentromeres joining sister chromatids separate and become individual chromosomesThey are dragged by fibers to opposite polesEnds when chromosomes stop moving
- 35. TelophaseOpposite of prophaseCondensed chromosomes disperse into tangle of materialNuclear envelope reformsSpindle breaks apartNucleolus becomes visibleAt the end 2 identical nuclei in one cell
- 39. CytokinesisHappens at the same time as TelophaseDivision of cytoplasmAnimal CellsCell membrane drawn inward until it pinches off (cleavage furrow) and forms 2 id daughter cellsPlant CellsCell plate forms between nucleiCell Plate develops into separate membrane Cell wall appears
- 45. Regulators of Cell CycleCyclinsProtein that regulates the timing of the cell cycle in eukaryotic cellsLevels of cyclins rise and fall throughout the cell cycleCyclin-dependent Kinases (cdks)Enzymes that are activated when they bind with cyclin and they make the cell cycle continue
- 46. RegulatorsInternalFactors within the cell that control cell cycleCyclin and CDKsAllow cell cycle to proceed only when certain processes have occurredReplication of chromosomesChromosome Attachment to spindle before anaphase ExternalFactors Outside the cellGrowth factorsmolecules that bind to cell surface that signal cell to divideSimilar cells have molecules that have opposite effect so that when it becomes to crowded, cells stop dividing
- 47. What happens when cells cannot control their cell division?CancerDisorder in which some of the body’s own cells lose the ability to control cell growthDisease caused by disruption of the controls of the cell cycleCancer cells do not respond to the signals that regulate the growth of most cellsSome do not respond to external controlsSome do not respond to internal controls
- 48. TumorA mass of cells that cannot stop dividing
- 49. BenigntumorABNORMAL MASS OF REGULAR CELLS THAT DO NOT LEAVE THEIR ORIGINAL SITEMalignanttumorMASS OF CELLS THAT RESULTS FROM REPRODUCTION OF CANCER CELLSThese cells send out signals (proteins) that tell the body to produce a new blood vessel at the tumor siteANGIOGENISISNow the tumor has a blood and nutrient supply as way as an escape route to the rest of the body!!
- 50. Metastasis (muh TAS tuh sis)SPREAD OF CANCER CELLS BEYOND THEIR ORIGINAL SITE
- 51. Cells break away from original tumor and spread to surrounding tissues via bloodstream or lymphatic vessels
- 53. What causes cells to lose control?Exposure to toxins (smoking/drugs)MutagensRadiation exposureUV radiation (sun)Viral infectionsGeneticHow…???
- 54. What exactly happens?Radiation is energyToo much energy can break up those delicate bonds that hold together DNADNAmRNAproteinProteins are those internal and external regulators of the cell cycle….you mess up the DNA that makes them you have BIG problemsCell divides uncontrollably
- 56. Cancer geneticsMutation of the p53 gene (on DNA)P53 gene controls the regulation of the cell cycle…if its mutated, then you cannot control cell cycle BRCA 1 gene is a tumor suppressor gene for breast cancerIf gene is mutated, then tumor formation can beginMutations in this gene does not necessarily mean the person will get breast cancer, but that they have an INCREASED risk for breast cancer
- 58. TreatmentsSurgery (before metastasis) ChemotherapyDrugs/medicines that target cells that divideIncludes cancer cells as well as regular dividing cell (hair, intestinal, skin cells, bone marrow cells)DIFFERENT TYPES:Antimitotic drugsSome prevent spindle formation while others freeze the spindle after formationNo MITOSIS…No new cancer cells!Drugs that stop DNA synthesis/replicationSome prevent unwinding of DNASome prevent cells from making nucleotidesSome inhibit attachment of thymine nucleotidesNo DNA replication…No new cancer cells!RadiationEnergy that kills all cells in a particular regionDestroys all remaining cancer cells at original site
- 59. Prevention is the Key!Avoid toxins!Use sun block!Get an unusual lumps or moles checked out immediately!