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Cell Growth and Division

Cell Growth and Division. Cell Growth. Living things grow chiefly because of two things. 1. The number of cells increases. 2. The size of each individual cell increases. Number 1 is actually due to number 2!. Volume vs. Area.

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Cell Growth and Division

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  1. Cell Growth and Division

  2. Cell Growth • Living things grow chiefly because of two things. • 1. The number of cells increases.

  3. 2. The size of each individual cell increases. • Number 1 is actually due to number 2!

  4. Volume vs. Area • The volume, the growth of the internal parts of the cell surpasses that of the area, or external parts of the cell.

  5. Limits • The growth is limited by two things • The instructions, DNA. • The amount of available materials.

  6. Cell division • The point at which the internal exceeds the external = division.

  7. Rate of growth In ideal conditions, E-coli can double its volume in just 30 minutes. In one day a single bacteria could produce a 14 Kg mass.

  8. In three days the mass of the bacteria would equal that of the…

  9. Disorderly growth • Cancer: a disorder in which cells have lost the ability to control their rate of growth.

  10. Cell Division • There are two main stages to division of Eukaryotic cells. • Mitosis • Cytokinesis

  11. Mitosis • The nucleus of the parent cell is divided into 2. • Each with the same number and type of chromosomes.

  12. Cytokinesis • The cytoplasm of the parent cell divides. • Two distinct cells are formed. • Daughter cells

  13. Chromosomes • Highly organized segments of genetic information. • Made up of chromatin.

  14. Chromatin • A specific combination of DNA and proteins.

  15. Chromatids • Each chromosome has two identical parts, chromatids. • Joined by a centromere.

  16. The two identical parts allow for the production of two identical cells.

  17. The process of cell growth and division is a cycle. Interphase

  18. Interphase • The period between cell divisions • 3 phases • G1, S, and G2

  19. G1: Cell growth • S: DNA replication • G2: Preparation for mitosis

  20. Mitosis (4 phases) • Prophase • Metaphase • Anaphase • Telophase

  21. Prophase (fig 8-12) • Longest phase • Centrioles take positions at opposite ends of the cell

  22. Spindle fibers form between the centrioles • Chromosomes attach to the spindle

  23. The nucleolus disappears • The nuclear envelope breaks down.

  24. Metaphase (fig 8-14) • Shortest phase • Chromosomes line up along the center of the cell.

  25. Anaphase (fig 8-15) • Centromeres split • Individual chromatids are pulled to opposite ends of the cell.

  26. Telophase (fig 8-16) • Final phase • Chromatids uncoil to reveal a mass of chromatin.

  27. Nuclear envelopes reform around the chromatin • A nucleolus becomes visible for each daughter cell

  28. Mitosis is complete!

  29. BUT, cell division is not!

  30. Cytokinesis • Animal Cells • The cell membrane moves inward pinching the cytoplasm into two cells.

  31. Each half contains a nucleus • And all necessary organelles • Plant Cells • A cell plate forms dividing the cell in half

  32. The cell plate evolves into a new cell wall for each cell.

  33. This is really the end!

  34. Scientific NotationM X 10n • A.1.) 1.0 X 10 -8 cm • A.2.) 1.0 X 10 10 cm • B.1.) 0.000002 cm • B.2.) 1,000,000 times greater

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