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Chapter 9 MITOSIS Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 9.1 The Cell Cycle **Orderly set of steps between eukaryotic cell divisions Why do Cells Divide? Growth Reproduction (in single celled organisms) Repair Control of the Cell Cycle G1 Checkpoint - Check to see if DNA is damaged G2 Checkpoint - Check to see if DNA is replicated properly M Checkpoint - spindle assembly checkpoint, check for alignment of chromosomes Apoptosis - programmed cell death, if any of the checks fail 9.2 Mitosis & Cytokinesis Mitosis - The division of the nucleus that results in identical complete copies of chromosmes packaged into two new nuclei Cytokinesis - The division of the cytoplasm that results in two daughter cells Interphase • Prophase • Metaphase • Anaphase • Telophase IPMAT Interphase: Resting Prophase: Chromosomes visible, spindle forms as centrioles move Metaphase: Chromosomes line up along equator Anaphase: Chromatids separate Telophase: Nuclear membrane forms on each side, cytokinesis begins **In plant cells, cytokinesis begins when a new cell wall forms between the two new cells. **In animal cells, the two new cells pinch and pull apart 9.3 The Cell Cycle and Cancer neoplasm: abnormal growth of cells benign: non-cancerous malignant: cancerous Cancer: cellular growth disorder that results from the mutation of genes that regulate the cell cycle Cancer cells ●lack differentiation ●have abnormal nuclei ●form tumors ●undergo metastasis & angiogenesis Mitosis produces 2 daughter cells The two daughter cells contain the exact same number of chromosomes as the original parent cell Daughter cells are DIPLOID HeLa Cells A HeLa cell (also Hela or hela cell) is a cell type in an immortal cell line used in scientific research. It is the oldest and most commonly used human cell line. The line was derived from cervical cancer cells taken from Henrietta Lacks, a patient who eventually died of her cancer on October 4, 1951. Article on Henrietta Lacks 1.Name the phases starting at the top. 1.Name the phase 2.Identify X 3.Identify Y 5. Name the phase 6. Name the phase 10. In humans, each cell (except sex cells) has how many chromosomes? ______ 11. After mitosis, how many daughter cells are produced? _______ 12. After mitosis (in a human cell), each daughter cell has how many chromosomes? _____ 13. How many phases are in MITOSIS? ___________ 14. Which phase of the cell cycle is the longest? _________ 15. During which phase does cytokinesis begin? __________