2. Chapter 8 Part Two Cell Growth and Reproduction

3. Cell Size Limitations  Cells vary in size and shape  The longest cells are nerve cells which can be up to 1m in length

4.  The cell with the largest diameter is the ostrich egg which is about 8 cm

5.  Most cells vary in size from 2 to 200 pm in diameter  http://www.cellsalive.com/how big.htm http://www.cellsalive.com/how big.htm

6. Factors that affect cell size  1. Diffusion  The larger the cell the longer for diffusion to occur  2. DNA  DNA serves as the blueprint for the production of proteins  A cell must have enough DNA to support the cell’s proteins needs

7.  Surface to volume ratio  As a cell size increases its volume increases much faster than its surface area

8. Surface area = 6 x 1x 1 or 6 Volume = 1 x 1 x 1= 1 Surface area = 6 x 2 x 2 or 24 Volume 2 x 2 x 2 or 8 Surface area increase 4x Volume increased 8x 1 2

9. Cell Reproduction  Cell theory states that all cells come from cells  Cell division is the process by which new cells are produced from one cell  Cells are continually growing, dividing and dying

10. Chromosomes  Chromosomes are vital to cell reproduction  Chromosomes are the carriers of the genetic materials from generation to generation of cells  Chromosomes are visible with a microscope just before cell division

11. Basic structure of a chromosome Centromere region chromatids

12. The Cell Cycle  The cell cycle is the sequence of growth and division  Periods of the cell cycle –The period of growth called interphase –The period of division called mitosis –The period of division called cytokinesis

13. A cell spends the majority of its life in interphase

14.  During interphase the cell grows in size and carries on metabolism  In late interphase the chromosomes are duplicated in preparation for cell division

15.  Stages of interphase  Gap 1(G1)- is the longest stage Chromosomes are uncoiled and not visible. Protein synthesis is rapidly occurring as the cell grows and develops

16.  Stages of interphase cont.  Synthesis (S) stage- the chromosomes are replicated in the nucleus and they divide to form identical sister chromatids

17. chromatid The chromosome is the entire structure while each leg is a chromatid

18.  Stages of interphase cont.  Gap 2 (G2) The chromosomes shorten and coil. Rapid protein synthesis occur as the cell prepares for mitosis In animal cells the centrioles replicates and prepares to form the spindle fibers

19.  Mitosis  Is the process by which two daughter cells are formed from a single parent cell  The daughter cells are identical to the parent cell  Occurs in eukaryotic somatic (non-reproductive) cells

20. Stages of Mitosis  Prophase- the longest phase of mitosis  the chromatin coils to form visible chromosomes  The nucleus disappears because the nuclear membrane and nucleolus disintegrate

21.  In animal cells the centrioles begin to migrate to opposite ends of the cell forming the spindle between them  In plant cells the spindle fibers form with out centrioles

22. Early prophase Late prophase

23.  Metaphase – short second phase of mitosis  The chromosomes become attached to the spindle fibers by their centromeres  The spindle fibers line up the chromosomes in the middle of the cell

24. Metaphase

25.  Anaphase- the third phase of mitosis  The centromeres split apart allowing the sister chromatids to separate  The spindle fibers shorten and pull apart the sister chromatids

26. anaphase

27.  Telophase- the final phase of mitosis  Begins when the chromatid reach the opposite poles of the cell  During telophase chromosomes uncoil, the spindle breaks down, and a new nucleolus and nuclear membrane are formed

28.  A new plasma membrane begins to form between the two new nuclei

29. Telophase

30.  Cytokinesis  The division of the cytoplasma  In animals, the plasma membrane pinches in along the middle of the cell  In plants, a cell plate is laid down across the cell’s midline and new cell walls form on each side of the cell plate

31. Cytokinesis

32. Plant CellAnimal Cell Interphase

33. Plant CellAnimal Cell prophase

34. Plant CellAnimal Cell metaphase

35. Plant CellAnimal Cell anaphase

36. Plant CellAnimal Cell telophase

37. interphase

38. prophase

39. metaphase

40. anaphase

41. telophase

42. cytokinesis

45. Mitosis animated videovideo