Sec.3, cell cycle & cell division

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The Cell Cycle and Cell Division Section, study well and solve the assessment at the End of that section.

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Sec.3, cell cycle & cell division

  1. 1. Cell DivisionAll cells are derived from pre- existing cellsNew cells are produced for growth and to replace damaged or old cellsDiffers in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants, & animals) 2
  2. 2. Keeping Cells IdenticalThe instructions for making cell parts are encoded in the DNA, so each new cell must get a complete set of the DNA molecules 3
  3. 3. DNA Replication DNA must be copied or replicated before cell division, Original DNA DNA is untwisted and strand separate. Every nitrogenous bases on the strands will pair up with its suitable base that floats in the nucleus. Each new cell will then have an identical copy of the DNA Two new, identical DNA strands
  4. 4. DNA ShapeDouble helix: 2 spirals wound around each other But joined in the middle
  5. 5. What’s Happening in Interphase?What the cell looks like Animal CellWhat’s occurring 6
  6. 6. Mitosis 7
  7. 7. Chromosomes in Dividing CellsDuplicated chromosomes are called chromatids & are held together by the centromere Called Sister Chromatids
  8. 8. Four Mitotic StagesProphaseMetaphaseAnaphaseTelophase 9
  9. 9. Mitosis• Prophase: • Chromosomes condense • Nuclear envelope disappears • centrosomes move to opposite sides of the cell • Spindle forms and attaches to centromeres on the chromosomes• Metaphase • Chromosomes lined up on equator of spindle • centrosomes at opposite ends of cell• Anaphase • Centromeres divide: each 2-chromatid chromosome becomes two 1-chromatid chromosomes • Chromosomes pulled to opposite poles by the spindle• Telophase • Chromosomes de-condense • Nuclear envelope reappears • Cytokinesis: the cytoplasm is divided into 2 cells
  10. 10. Cytokinesis Means division of the cytoplasm Division of cell into two, identical halves called daughter cells. In plant cells, cell plate forms at the equator to divide cell. In animal cells, cleavage furrow forms to split cell 11
  11. 11. CytokinesisCleavage furrow Cell plate in in animal cell animal cell 12
  12. 12. Revise and Test YourselfReview ofMitosis 13
  13. 13. Name the Mitotic Stages: Interphase Name this?Telophase Prophase Name this? Metaphase Anaphase http://www.cellsalive.com/quiz.htm 14
  14. 14. 15

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