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10.1 Pre-Read Questions

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  1. 10.1 Pre-Read Questions • Name 2 limitations to cell growth. • How does DNA limit cell growth? • Why is the ratio of surface area to volume important? • Describe the process of cell division.

  2. Ch 10: Cell Growth and Division 10.1: Cell Growth

  3. Cells • Does not continue to grow bigger • Cells just continue to produce more cells

  4. Limits to Cell Growth • 2 main reasons • Larger a cell becomes, the more demands the cell places on its DNA

  5. Limits to Cell Growth • 2 main reasons 2. Cell has more trouble moving enough nutrients and wastes in and out of cell

  6. Reason #1 DNA “overload” • DNA = information that controls a cell’s function • if cells grow, DNA does not make extra copies • DNA would not be able to serve the needs of the cell

  7. Reason #2: Exchanging Materials • how fast materials leave or enter the cell depends on surface area • food and oxygen depend on cell volume

  8. Ratio of Surface Area to Volume • as surface area increases, its volume increases at a faster rate

  9. Ratio of Surface Area to Volume Consequence = cells have a more difficult time to move needed materials in and waste products out

  10. Cell Division • how cells reproduce • one cell divides into 2 new cells • daughter cells

  11. Cell Division before cell division - cell copies DNA • Each daughter cell gets own copy of DNA

  12. 10.2A 12 / 5 / 06

  13. 2 Stages • Mitosis = division of the cell nucleus • Cytokinesis = division of the cytoplasm

  14. Mitosis • asexual • source of new cells

  15. Chromosomes • carries the genetic information • consists of DNA • cells have specific number of chromosomes

  16. Chromosome • not visible until cell division • replicated before cell division • chromosomes change form to chromatids

  17. Chromatids • Separate from each other and go into daughter cells • attached at a centromere • located near the middle of the chromatids

  18. Centromere Chromatid

  19. Cell Cycle • cell reproduction • forms two daughter cells • in between period = interphase

  20. Cell Cycle: 4 phases • consists of 4 phases • M phase = mitosis and cytokinesis • S phase = chromosome replication (S = synthesis) • G1 and G2 (G = gap) -- growth and activity

  21. Interphase • 3 of the 4 phases occur • G1 • S phase • G2

  22. G1 Phase • cell growing • increase in size and synthesize new proteins and organelles

  23. S Phase • chromosome replication • proteins synthesized

  24. G2 Phase • DNA replication complete at beginning • shortest phase

  25. G2 Phase • organelles produced • prepare for cell division

  26. 10.2 Post Read Questions • Describe the 2 stages of cell division. • Draw a chromosome and label and describe its parts. • What are the different phases of interphase? Describe each one. • What is the cell cycle?

  27. 10.2 B 12 / 06 / 06

  28. Interphase • In between periods of cell division • Cell growth and DNA replication occur

  29. Prophase • first and longest phase (50%-60%) • chromosome becomes visible • centrioles take position on opposite sides of nucleus at the centrosome

  30. Prophase • Centrioles lie in centrosome so they can organize the spindle • Spindle = fanlike microtubule structure that helps separate the chromosomes

  31. Prophase • end = chromosomes coil and nuclear envelope break down

  32. Metaphase • lasts only a few minutes • chromosomes line up across the center of the cell

  33. Metaphase (cont) • microtubules connect the centromere of each chromosome to the two poles of the spindle

  34. Anaphase • centromeres that join the sister chromatids split into individual chromosomes and are moved apart to opposite poles

  35. Telophase • chromosomes become dense material • spindle breaks apart • nucleolus appears

  36. Cytokinesis • Division of cytoplasm • usually occurs the same time as telophase • Animal Cell = cell membrane draw inward and pinched off • Plant cell = cell plate forms midway between the 2 nuclei; cell wall appears

  37. T I P M A ROPHASE ETAPHASE NAPHASE ELOPHASE NTERPHASE

  38. A B E C D Put the pictures in order

  39. A B E C D ANSWER

  40. Ch 10 Review Questions (Cont) • What is cytokinesis? When does it occur? • Compare how cytokinesis works between animal and plant cells. • Describe metaphase. • Describe anaphase. • If you were to look at a picture of telophase and anaphase, how can you distinguish the difference between the two?

  41. 10.3 12 / 7 / 06

  42. Review: Cell Cycle • Preparing for Cell Division • INTERPHASE • G1 • S • G2

  43. Review: Cell Cycle • Steps of Cell Division • Mitosis • Prophase • Metaphase • Anaphase • Telophase / Cytokinesis

  44. Look at Figure 10.7 • Observe what is going on • What is happening in each step?

  45. Cyclin • protein • regulates the timing of the cell cycle in eukaryotic cells

  46. Regulatory Proteins • Two types • Internal Regulators • External Regulators

  47. Internal Regulators • proteins that respond to events inside the cell • signals cell cycle to continue ONLY WHEN OTHER THINGS ARE COMPLETE