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Cell Growth and Division

Explore the process of cell growth and division, including the concepts of DNA overload, exchanging materials, and the cell cycle. Learn about the importance of surface area to volume ratio and the stages of mitosis.

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Cell Growth and Division

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  1. Cell Growth and Division Biology Unit 4 Ms. Lew

  2. Vocabulary (p. 90-91) • Cell Cycle • Chromatin • Chromosome • DNA overload

  3. Key Concept: • Most living things grow by __________________________. On average, the cells of an adult animal are ______________ the cells of a young animal. Making more cells No larger than

  4. List two reasons why cells divide rather than continue to grow larger: • __________________________________ • __________________________________ DNA Overload Exchanging Materials

  5. DNA Overload: • DNA overload is when the DNA has too many tasks to do (such as making proteins) and not enough DNA to get the job done efficiently. To prevent DNA overload cells stay small to limit a cells work load.

  6. Materials exchange becomes more difficult in large cells: • Materials move into and out of cells Cells need to take in materials such as oxygen, water and glucose. Cells need to get rid of materials such as carbon dioxide, salts, other waste. • Large cells lose efficiency in this process – surface area and volume do NOT increase at the same rate.

  7. How do you determine the surface area of a cube? • Length x Width x 6

  8. How do you determine the volume of a cube? • Length x Width x Height

  9. How do you determine the ratio of surface area to volume? • Surface Area / Volume

  10. Why is the ratio of surface area to volume in a cell important? This ratio is what determines HOW MANY and HOW FAST substances can enter the cell. As a cell grows, its SA/V ratio DECREASES, and the cell can no longer be supplied enough nutrients, and stops growing

  11. Door analogy • More doors, less time it takes for people to get out of classroom.

  12. Find the surface area, volume and surface area to volume ratio of the following cube-shaped cells: 2cm 4cm 6cm 24 cm2 96 cm2 216 cm2 8 cm3 64 cm3 216 cm3 3:1 1.5:1 1:1

  13. Vocabulary (p. 90-91) Must find definitions on your own by Notebook check #2 • Cell Cycle • Chromatin • Chromosome • DNA overload • Interphase • Sister Chromatid • Spindle Fiber

  14. What is the cell cycle? • During the cell cycle, a “parent” cell grows and divides to form 2 “daughter” cells. • The cycle has three main stages • Interphase • Mitosis • Cytokinesis

  15. Remember the two reasons why cells divide rather than continue to grow larger: • __________________________________ • __________________________________ DNA Overload Exchanging Materials

  16. The Cell Cycle • Animation

  17. G1 M S G2

  18. Interphase – G1 , S & G2 • During Interphase cells: • Grow to mature size • Mitochondria and chloroplasts are duplicated • Replicate (copy) DNA • Each cell needs instructions • Prepare for cell division • Cell grows • Most of a cells life is spent in Interphase.

  19. Chromosomes • Are made of DNA • Each chromosome consists of sister chromatids attached at a centromere • Each sister chromatid is an exact copy

  20. Mitosis – M phase • The cells nucleus divides into two nuclei • There are four phases • Prophase • Metaphase • Anaphase • Telophase P M A T

  21. Animal Cell Mitosis- Video

  22. Prophase • 1st stage of Mitosis • Chromatin condenses into chromosomes • Centrioles separate and a spindle fiber begins to form. • Nuclear membrane breaks down

  23. Prophase

  24. Metaphase • 2nd Phase of Mitosis • Chromosomes line up in the middle of the cell. • Each chromosome is connected to a spindle fiber.

  25. Metaphase

  26. Anaphase • 3rd Phase of Mitosis • The sister chromatids separate at the centromere and move to opposite ends of the cell.

  27. Anaphase

  28. Telophase • 4th Stage of Mitosis • Chromosomes gather at opposite ends of the cells and lose their shapes (return to chromatin form) • Two new nuclear membranes form, one for each cell.

  29. Telophase

  30. Stage 3: Cytokinesis • The cytoplasm pinches in half. • Each daughter cell has an identical set of duplicate chromosomes

  31. Cytokinesis

  32. Overview sim • http://www.sumanasinc.com/webcontent/animations/content/mitosis.html

  33. Plant cell mitosis • https://www.youtube.com/watch?v=aDAw2Zg4IgE

  34. And Another one… • https://www.youtube.com/watch?v=KzBoIAMVUSY

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