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The Cell Cycle

The Cell Cycle. Why are cells so small??. What limits the size of a cell?? Most cells are between .002 - .2 millimeters. What limits the size of a cell?. Diffusion Very fast and efficient over short distances Becomes slow and inefficient as the distances become larger

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The Cell Cycle

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  1. The Cell Cycle

  2. Why are cells so small?? • What limits the size of a cell?? • Most cells are between .002 - .2 millimeters

  3. What limits the size of a cell? • Diffusion • Very fast and efficient over short distances • Becomes slow and inefficient as the distances become larger • Cells would die before nutrients could reach the organelles if the cell was too big

  4. What limits the size of a cell?? • Surface Area – to – Volume Ratio • As cell size increases, its volume increases much faster than surface area • Example: If cell size doubles, the cell would require 8 times more nutrients, but the cell membrane would only increase by 4 times. This would mean that the cell doesn’t have enough room (cell membrane) to diffuse.

  5. What limits the size of a cell?? • DNA • There’s a limit to how fast DNA can make proteins • If you have a large cell then the DNA can’t make proteins fast enough for the cell.

  6. The Cell Cycle • Cell Reproduction • One cell (parent cell) reproduces to make 2 identical cells (daughter cells) • 5 steps in this process

  7. What is Mitosis • Mitosis is…THE PROCESS BY WHICH A CELL’S NUCLEUS DIVIDES!

  8. Before Mitosis… • Interphase • This phase is broken down into 3 subphases • G1 = Cell grows in size and organelles replicate • S = DNA duplicates itself (DNA Replication) • Chromatin duplicates – long coily strands of DNA that become wrapped up • G2 = Rapid Growth before dividing • Cells spend most of their time in this phase

  9. Interphase

  10. Interphase

  11. Interphase

  12. Interphase

  13. Mitosis • Prophase • A.) Chromatin organizes itself into chromosomes made up of 2 sister chromatids attached by a centromere • Sister Chromatids – A chromosome and its duplicated twin • Centromere – rubber band structure that joins the 2 sister chromatids together

  14. Prophase • B.) Nuclear membrane breaks down • Nucleus dissolves • C.) Centrioles move to opposite ends of the cell (poles) • Centrioles – cylinder structures that will reel in the chromatids • D.) Spindle fibers form • Spindle fibers – football shaped set of ropes that will attach to the centrioles and the chromatids • Made of microtubules

  15. Prophase

  16. Prophase

  17. Prophase

  18. Prophase

  19. Prophase

  20. Prophase

  21. Prophase

  22. Mitosis • Metaphase • Spindle fibers attach to centrioles and sister chromatids at their centromeres. • Chromosomes line up in the middle of the cell • Line up on the metaphase plate/equator.

  23. Metaphase

  24. Metaphase

  25. Metaphase

  26. Metaphase

  27. Metaphase

  28. Metaphase

  29. Metaphase

  30. Metaphase

  31. Metaphase

  32. Metaphase

  33. Mitosis • Anaphase • The centromeres split apart and the sister chromatids separate from each other • The spindle fibers pull the chromatids toward the poles

  34. Anaphase

  35. Anaphase

  36. Anaphase

  37. Anaphase

  38. Anaphase

  39. Anaphase

  40. Anaphase

  41. Anaphase

  42. Anaphase

  43. Anaphase

  44. Anaphase

  45. Mitosis • Telophase • Chromatids reach the poles • Chromosomes unwind • Spindle fibers break down • Nucleus reforms • Cell begins to split • Cleavage furrow

  46. Telophase

  47. Telophase

  48. Telophase

  49. Telophase

  50. Telophase

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